GrowWeedEasy.com teaches you how easy it is to grow weed. Growing weed can be easy when you know what to do, but most “how to grow marijuana” tutorials make it seem like you need a degree in horticulture.

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Who Made GrowWeedEasy.com?

Grow Weed Easy.com was started in 2010 by home growers Nebula Haze and Sirius Fourside. Together, they built a free online “encyclopedia of cannabis home grow” with 650+ expert home cannabis cultivation tutorials about every aspect of growing weed.

GrowWeedEasy.com is now the biggest and most comprehensive source of free home grow information in the world.  We show you how easy it is to grow your own marijuana at home.

The GrowWeedEasy.com Ethos

Our Goal: You grow as much top-shelf weed as possible, with as little time and effort needed to grow your desired yields and cannabis bud quality.

Whether you’re a total beginner who wants to start growing cannabis indoors for the first time, or an experienced grower who wants to upgrade your skills to Pro level, this website was built for you.

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If you want dense, beautiful, great-smelling weed, our new digital book gives you our complete harvest system. Follow the straightforward instructions and massively upgrade your results every harvest. A few small changes can make all the difference.

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If you’re reading this right now, you want to grow great cannabis at home.

Cannabis plants isn’t a regular house plant, but learning how to grow isn’t as complicated growers make it seem. We’ve spent the last 16 years breaking down the home grow process so anyone can learn it.

The key to consistent harvest results is simple: follow a proven system developed for home growers.

You could waste an entire grow learning through trial and error…

Or take the shortcut and harvest a sea of fat, dense, beautiful buds that smell great. At home!

Follow our 5-week course and get walked through each part step-by-step. Build by experienced home growers and honed with hundreds of students since 2019, we ensure you achieve great results on your very next harvest.

Learn How To Grow Top-Shelf Weed at Home!

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You may be asking yourself these common growing questions:

“How do I grow marijuana indoors?”

Read this guide on how to grow marijuana indoors. Or check out this article to learn what materials you need to get started growing your own marijuana!

Luckily, it’s really easy to get a cannabis seed to sprout!

“How much money will it cost to get started?”

If you’re considering growing weed, it costs as little as $300 to get started growing or a bit more for a semi-automatic, high-yielding bubbleponics grow system. See examples of yields to expect, electricity use & startup costs for different setups. Read this article to see even more growing styles with different price ranges.

“Where can I get marijuana seeds?”

Check out our How to Buy Marijuana Seeds Online Guide (with delivery to every state of the USA) to safely get your hands on good genetics. Starting with good seeds lets you choose the looks, smell, and effects of your buds!

Learn where it’s safe to buy cannabis seeds online (2026 update).

What do good cannabis seeds look like?

Learn about the best marijuana beginner strains and how to research and find the right strain.

Cannabis buds are generally green, but can also be pink or purple with certain strains.

“How much will electricity cost each month?”

If you’re just growing a few marijuana plants for personal use, it will cost you $20-$100+/month for electricity, depending on what grow lights (electricity) and nutrients you use. On average, I’d say a hobby-size grower might pay about $50/month to grow, but it depends greatly on your setup and local electricity costs! How much will electricity cost each month?

“How can I increase my marijuana yields?”

We have quite a few techniques to choose from or combine! See some of our most popular pages:

• Super Cropping – A simple technique to bigger yields
• Simplest Guide to Growing Short & Bushy Marijuana Plants
• LST (Low Stress Training) – Training your plants can easily double your harvest!
• Or check out our page on the controversial defoliation technique

Even More Ways to Increase Cannabis Yields

1. Increase Light Intensity (plus choose right light for desired yields & possibly add CO2)
2. Manipulate How Plants Grow (a free way to yield more bud indoors)
3. Provide Right Nutrients (low Nitrogen in the flowering stage, and remember sometimes less is more!)
4. Control Growing Environment (let the growing environment work for you)
5. Harvest Plants Properly (most importantly, don’t harvest early!)
6. Lastly, it’s important to remember that the strain has a major effect on yields!

Two small cannabis plants can yield several ounces of premium weed!

“How can I grow weed privately?”

Read guide on growing weed indoors without anyone knowing. But remember the most important factors to stealth growing: “No tell, no smell, no sell.” Never tell anyone, not even your best friend, that you’re growing. Be on top of preventing smells, and never ever sell cannabis. Breaking one of those 3 principles is how 99% of growers get found out!

“What if my plants get sick?”

The most common issue a grower runs into is a pH imbalance. Barring that, your marijuana plants likely either have a nutrient deficiency, heat or light stress, or are being attacked by some sort of marijuana mold, pest or bug. Whether you call it weed, cannabis, sinsemilla, skunk, pot, marijuana, or something else, the plant known as Cannabis Sativa is a hardy weed in the wild and can actually be easy to grow indoors at home when you know what to do.

Growing Medical Marijuana

“Medical marijuana” has become a household name. The body of evidence for medical marijuana in the treatment of cancer and other illnesses is growing every day. And for those who need medical marijuana, growing weed indoors is the perfect way to ensure a safe, regular supply of buds, for cheap.

In fact, when you grow weed indoors for personal use, you often end up with way too much. If you catch the growing bug like I did, and if you start enjoying the process of tending your cannabis garden just for the sake of gardening, you’re going to have to find a way to press, cook, freeze, and concentrate all your extra buds. 🙂

As you probably know, both medical marijuana and recreational cannabis have been decriminalized or legalized in many places around the world and weed is becoming legal in more places every day! Yet there still aren’t many simple indoor “how to grow weed” guides for beginners (even for those who legally grow, such as medical marijuana users and those who live in places where marijuana is legalized for personal use).

If so, I know how you feel. It can be hard to weed out all the bad information on the internet and find well-researched, free tips or instructions on how to grow your own cannabis. That’s why Grow Weed Easy.com aims to be a simple online resource that explains from start to finish what you need to do when growing cannabis so you can learn how to grow cannabis with great yields and potent buds, even if you only have a small grow space like a closet or even a computer case.

We’ve grown cannabis out of closets and have gotten ounces of buds and you can too. Grow Weed Easy.com covers many popular cannabis cultivation topics, including:

• A comparison between different cannabis grow lights including experience-based information about LED grow lights
• A page that teaches you the basics of how to grow weed
• Detailed how-to weed growing tutorials
• How to start growing weed tomorrow  (simplest cannabis growing guide!)
• Grow 4 oz with a 100W LED <– An Easy Way to Start Growing!
• Our famous grow guide that teaches you how to grow weed using bubbleponics (hydro).

Start Growing Weed Today!

Grow Weed Easy is run by a panel of experienced cannabis growers, including the founders Nebula Haze and Sirius Fourside, who originally teamed together to bring you GrowWeedEasy.com. Due to the demand for more marijuana growing information, we’ve also started an inbox magazine all about how to grow weed, with additional tutorials, tips, and tactics sent to you each week. Simply sign up to start getting free expert growing articles delivered to you! All the information available at GrowWeedEasy.com is completely free and we regularly update the site and make new additions.

Looking for a growing book?

If you are interested in doing a bit of reading or would like to know more about the science behind marijuana hydroponics or horticulture, I strongly recommend viewing our page of Marijuana Grow Book Reviews. Read reviews of marijuana grow books. We would love to hear about your experiences with growing cannabis. Whether you are a pro grower already or are just starting your first plant, we have learned so much from our readers both beginners and masters! If you have any suggestions, comments, concerns, or just want to ask some questions about your marijuana grow, please contact us!

Happy Growing!
Nebula Haze & Sirius Fourside

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The post Grow Weed Easy – Learn How to Grow Cannabis Tutorials appeared first on Grow Weed Easy.

Table of Contents

Which Cannabis Growers Should Use a Grow Tent?

Create the Perfect “Pop-Up” Environment

What Size Grow Tent?

How to Set Up a Grow Tent for Ultimate Stealth

Who Should Use Grow Tents?

Grow tents keep things simple for a hobbyist cannabis grower. A 4’x4′ grow tent can produce 1-2 pounds per harvest with the right grow light, and as a bonus, a grow tent with a carbon filter keeps all smells inside so no one knows you’re growing! Although grow tents are not designed for huge marijuana grow operations, they are excellent for hobby growers who are growing weed in a room or closet.

Cannabis grow tents come in many sizes, to fit your current grow goals and space limits.

For growers who want to grow a ton of weed at a time, there are also bigger cannabis grow tents, up to the size of a small room!

Pros of Growing Cannabis in a Grow Tent

• Relatively Cheap – Prices are around $70-150 for your average grow tent. Setting up a grow space to have all the same characteristics (reflective walls, air-tight vents, lightproof, a waterproof tray at the bottom to catch spilled water, etc.) can easily cost the same amount or more. Plus it’s difficult to DIY a space so that it works as well as a grow tent (which has been designed for this purpose) and it will often take more time, planning, and effort than simply buying a pre-made tent.
• Easy & Quick to Set Up – Assembling your grow tent and getting completely set up to start growing weed will take about an afternoon and can be done by just about anyone (full instructions below). Overall, the work of setting up a grow tent reminds me of putting together an old-fashioned camping tent, only weed comes out of it a few months later!
• Stealth – A grow tent prevents smells and light from escaping the tent when set up properly, and can be tucked away in a big closet or the corner of a room without necessarily drawing a whole lot of attention.
• Perpetual Harvest – Grow tents work very well if you want to keep two separate grow spaces, for example, if you want a separate vegetative and flowering chamber for a perpetual harvest. Grow tents create a completely self-enclosed environment that can be managed separately.
• Helps Prevent Bugs – The intake holes of most grow tents are covered with mesh, which allows air to pass but stops many insects. This helps prevent incidental bugs like spiders or carpenter beetles from getting to your plants. A grow tent with strong grow lights is also a pretty hot and inhospitable environment for many cannabis pests!
• Keeps Buds Clean – In addition to preventing bugs from getting on your plants, the mesh intake holes help keep out dust and impurities. The sticky trichomes on cannabis buds are surprisingly good at holding on to fibers, animal hair, and anything that floats by. A surprising amount of random debris can get onto your buds even if you keep your grow room pristine. A grow tent helps keep buds clean and looking good!

Example of a happy cannabis plant in a grow tent.

Some grow tents don’t look particularly suspicious. On the left is a homemade stealth grow cabinet and on the right is a 2’x4’x5′ grow tent that looks vaguely like a clothes wardrobe. They’re just about equally nondescript!

When all is said and done, a stealth cabinet with fans on the inside (even one done very professionally so it’s completely lightproof) is only marginally more stealthy than a black grow tent with a zipper down the middle. When it comes to stealth, don’t expect any grow tent or cabinet to be stealthy enough for someone to be hanging out in your room without noticing the fact that it’s emitting light/noise/heat. Instead, you’re looking for something that can fool someone who is quickly passing by it for a moment or two.

Grow tents also let you easily set up a perpetual marijuana harvest. This grower (Manzfoo) keeps young plants in the purple LED tent, and older plants in the yellow HPS tent. As soon as he harvests the big plants, he rotates in the young ones and starts a new batch. This lets him harvest every 2 months or so!

If you’ve seen the examples and want to keep it simple and get a grow tent, here’s more information on how they quickly create the perfect environment for your growing marijuana plants!

Quickly Create the Perfect Cannabis Environment

When used correctly, a grow tent lets you recreate nature under its ideal conditions! Possibly the most challenging part of being able to grow cannabis in these ideal conditions is getting set up. However, once everything is set up, it’s mainly a matter of planting a seed and watering your plants until you harvest bud!

If you’re trying to create a cannabis growing environment from scratch, you may have to do some DIY which can feel overwhelming if you’re just getting a grasp on growing. Utilizing a grow tent takes care of a bunch of environmental factors in one fell swoop.

• Maximize Your Grow Lights – A grow tent has reflective walls and the reflectivity is equal to or often even better than what you could do yourself. Reflective walls ensure all the light from the grow light reaches your cannabis plants, which can increase your yields.
• Designed for Common Grow Equipment – It’s easy to hang and adjust your grow lights, hook up your fan, find ports and vents, etc. A grow tent accounts for most growing situations.
• Light Proof – A grow tent is constructed to prevent light from leaking in or out of the tent. Not only does this help your plants (cannabis needs complete darkness at night to make as many buds as possible), but it also prevents light from spilling out; you don’t want to possibly alert others that there are some very bright lights inside your home! Sometimes DIY light proofing a space can be tricky, and a grow tent takes that problem out of the equation.
• Waterproof & Easy to Clean – A grow tent usually has a waterproof floor that contains regular spills so you don’t have to worry about water leaking out onto your floor. It’s also easy to wipe down the walls and floor of a grow tent, making it simple to keep things clean.
• Designed for Airflow – The sealed nature of the tent combined with vents and air-ports make it so you can set up a whirlwind of air in the tent simply by installing a strong exhaust fan in one of the included ports. This constantly pulls fresh air in to circulate through the tent from the intake vents near the floor, replacing all the air in just minutes while giving plants plenty of CO2 and preventing problems from heat buildup.
• Smell-Proof – Grow tents make it really easy to take advantage of a carbon filter. The negative air pressure caused by the sealed space prevents any smells from leaking into the home as long as the carbon filter is attached, the exhaust fan is on and the doors are kept closed.

At its simplest, a grow tent just needs an exhaust fan and a grow light. At this point, you’ve already created a great cannabis-growing environment! See a grow journal in this setup!

What Size Grow Tent for Your Cannabis Grow?

There are hundreds of models of grow tents, and they come in many different sizes. It can be confusing to know which one to get for your situation, and which ones are best overall. This should help clear things up!

Best Hobbyist Sizes – 2’x2′, 2’x4′, and 4’x4′

When it comes to cannabis grow tents, three of the most common sizes (in the US) for hobbyist growers are the 2’x2′, 2’x4′, and 4’x4′ tents. These are also made to fit the most common grow lights.

I believe a 2’x4′ is one of the best sizes for new growers because it gives you enough space for decent yields (get up to several ounces a month) but it isn’t big enough to be overwhelming. You get easy access to all the plants, including the ones in the back, but still get all the advantages of a full-size grow light. You can start with a small LED grow light in this size tent and still have room to eventually upgrade up to a 300W grow light.

For bigger growers, a 4’x4′ grow tent is great because it can be used with the next class of grow lights up to some of the biggest grow lights. It can support a 600-1000W HPS or LED grow light as long as it’s 6-7′ tall.

If you want to double your yield from a 2’x4′ but don’t want to have to set up a whole grow room, a 4’x4′ is the way to go! It’s big enough for monster yields (a pound or more!) but still small enough to be manageable by just one person.

Height Helps – At least 4-5′ tall, and 7′ is better

Short spaces are difficult to grow in because you have to worry about your cannabis plant “growing into” the grow light. A 6′ tall tent will support up to a 300-400W grow light, and even with smaller grow lights, more height makes things a little easier. Having an area that is 7′ tall makes it unlikely you’ll ever be limited by the height of your grow space. A little extra height can increase your potential yields, in some cases, because a taller space lets you support more powerful grow lights and grow larger plants.

Short marijuana plants can only yield so much even if they’re completely covered in bud.

Extra height lets you use more powerful lights and grow taller plants (with bigger, longer buds!)

Cannabis Grow Light Compatibility

• 2’x2’x4′ – LEDs up to 100W.
• 2’x4’x5′ – LEDs up to 200W, 250W HPS
• 2’x4’x6′ (same size but taller) – LEDs up to 300W, 250W or 400W HPS
• 4’x4’x7′ – LEDs up to 650W, 600W or 1000W HPS

Examples & What to Look For

It can be tempting to try to get a really expensive grow tent with all the “bells and whistles” because you want to give your plants the best possible home! But honestly the cheapest grow tent has 90% of the features of a far more expensive grow tent. If you’ve never grown marijuana before and are reluctant to invest a lot of money, I recommend starting cheap when it comes to tents!

If possible, I recommend getting a tent that’s as tall as you can support so you never have to worry about running out of height. A 6′ tall grow tent easily supports up to a 300W or even 400W grow light. However, taller tents are relatively rare and it’s much more common to see grow tents that are only 5′ tall or shorter. The shorter versions will also do the trick (and can support bigger lights if you have a great exhaust system to vent heat and use careful plant training). Another advantage is that smaller tents are a little less conspicuous looking and people sometimes mistake them for a cheap Ikea-style clothing wardrobe. Just remember, with a short tent, to keep a close eye on plant height to make sure you don’t run out of headroom as plants get taller.

2’x2’x4′ – Example of Cheap Yet Effective 2’x2’x4′ Grow Tent (~$55) – I love the CoolGrows branded tents. I’ve tried them in a few different sizes and they are generally higher quality (better zippers, more sturdy) and yet cost less on average than many other brands. However, almost any grow tent by any brand works well to grow cannabis plants.

Grow Light Compatibility

• Small LEDs (up to 100W power draw) like Spider Farmer SF-1000

Spider Farmer SF-1000 LED grow light in a 2’x2′ grow tent. Check out the full setup.

2’x4’x5′ – Example of Cheap Yet Effective 2’x4’x5′ Grow Tent (~$90) – Vivosun branded tents are inexpensive and get the job done. However, almost any grow tent by any brand should do the trick.

Grow Light Compatibility

• Small LEDs (up to 200W power draw) like Spider Farmer SF-2000

Spider Farmer SF-2000 LED grow light in a 2’x4′ grow tent

2’x4’x6′ – Example of Cheap Yet Effective 2’x4’x6′ Grow Tent ($100) – This is the same size except for a bit taller. The extra height is useful in case a plant grows unexpectedly tall, or if you have a grow light that needs to be kept far from plants like some LEDs.

Grow Light Compatibility

• Mid-size LEDs (made for 2×4 size, typically 200-300W power draw and dimmable)
  • 200W LED – Spider Farmer SF2000
  • 300W – Mars Hydro TSL2000 or newer Mars Hydro SP3000
• HID grow lights – these get hot!
  • 400W HPS (dimmable 400W MH/HPS fixture plus 400W HPS bulb)
  • 315 CMH/LEC (dimmable 315 CMH fixture plus 315 CMH Bulb)

An example of marijuana plants I grew under the Mars Hydro TSL2000 in a 2’x4’x6′ Grow Tent

Exhaust Fan

At this size, grow lights put off significant heat that will raise the temperature in the tent by several degrees. Luckily it’s an easy fix. Get a 6″ exhaust fan to vent the heat out of the tent and bring in fresh air for your plants. Full instructions with pictures are below. I use the AC Infinity S6 exhaust fan (big and expensive but effective and quiet). Before that, I used a 6″ iPower exhaust fan (smaller and cheaper but much louder).

4’x4’x7′ Tent – 4’x4’x7′ Cheap But Effective Grow Tent ($80) – Another CoolGrows tent. This size tent can support even the legendary 1000W HPS but I personally think it’s the perfect size for a 600W HPS or LED grow lights with a total of 500-700W power draw. LED examples that would fit this tent:

Grow Light Compatibility

• Large LED fixture or two mid-size LEDs (450-700W total power draw and dimmable)
  • 480W LED – – Mars Hydro FC-E4800 (great results and produces less heat than most LEDs for a 4’x4′)
  • 600W LED – HLG 600 R-Spec (I’ve received excellent bud quality and high potency when I’ve grown weed under this light)
• HID grow lights
  • 600W HPS (dimmable, on a 6″ hood”) hooked up with 6″ ducting to a 6″ exhaust fan.
  • 630W CMH (dimmable, double 315W bulbs) hooked up with 6″ ducting to a 6″ exhaust fan.

Exhaust Fan

This much grow light power puts off a ton of heat. You need an extra strong 6″ exhaust fan like the Vivosun 6 inch 390 CFM fan and carbon filter kit (this kit actually includes a carbon filter and ducting so you can set your tent up to filter all smells) and if you want a quieter fan you’ll have to bump up to the 8″ size of AC Infinity as the 6″ version isn’t strong enough.

How to Set Up a Grow Tent for Stealth

What You Need

• Grow Tent (examples above)
• Grow Light
• Exhaust Fan
• Possibly Ducting
• (Optional) Carbon Filter (get this if you want to filter smells)

1.) Clear Space & Put Together Tent

Before getting started, take a minute to clean up the space where you will be building your tent. It’s easier to do it all in the beginning as opposed to while you’re working. Make sure to put together your tent at its final destination. You don’t want to build it only to realize it doesn’t fit through the doorway 🙂

Build tent at the place you plan to keep your grow tent. You don’t want to move it after it’s been assembled.

Lay out all the parts. Your grow tent should also come with directions.

Start assembling grow tent according to instructions. The directions should tell you which pole to put where. If you’ve ever put together a camping tent, this should seem familiar.

First you build the base.

Add the side poles. If you get confused, the poles should be labeled, and the directions will tell you which one goes where.

Add the top poles. You’ll notice you add two extra poles crosswise. These give you a place to easily hang your grow light. The full frame is now complete. Now you need to put on the reflective covering, kind of like giving your tent a jacket. Set the frame in the bottom.

Pull the jacket over the bars.

Add the waterproof tray to the bottom. This can catch up to several gallons of water, which protects your floor in case you ever spill water in the tent.

Your tent is now fully assembled!

2.) Hang Grow Light

It can be difficult choosing exactly which grow light you want, but once you’ve made your decision at least it’s easy to hang your light. Compare different grow lights

Example of LED Grow Light Hanging In Tent with Rope Ratchets

The best way to hang your grow light is using rope ratchets if you can; they are cheap and easy to set up. Your grow light may have come with some, or you may need to get them separately.

Rope ratchets make it incredibly simple to adjust your lights at any time without the chance of dropping the light on your plants. They let you quickly and easily move your grow light up or down. This can be useful if you want better access to the back of the tent without the light beaming on your head, or even just to take better pictures of your plants.

Make sure whatever you use to secure the lights (again, use rope ratchets!) can handle at least twice the weight of your grow light, just to be safe!

Cheap rope ratchets allow you to move a grow light up and down with a few clicks, so you never need to hold up your light or worry you might drop your light on your plants. This ones can hold up to 150 lbs, which should be plenty for any modern grow light.

3.) Hang the Exhaust Fan

Hang the exhaust fan with rope ratchets from the top bars inside the tent to help muffle the sound of the fan running. This is also the most efficient setup for removing heat because it creates short straight path for the air to leave the tent.

Use strong nylon rope or rope ratchets to hang your exhaust fan inside the grow tent from the top bars to dramatically reduce sound and vibration. Your fan will sound louder if it’s located outside of your tent and not hanging.

These days, most growers will be using LED grow lights, which have heat sinks that help direct heat up and away from your plants. This means your exhaust fan, which is located near the top of the tent, should already be well positioned to remove extra heat.

If you’re using a grow light that has an air-cooled hood that contains all the heat, like many MH or HPS grow lights, you can connect the exhaust fan to the hood directly for extra efficient cooling. This lets you vent hot air directly out of the tent so heat is never beaming down onto your plants.

Learn how to set up a hidden exhaust for MH/HPS grow lights.

You can continue ducting out a window to vent the heat completely out of the room

For the best results with any grow light, make sure there is a way for fresh air to get in. Grow tents almost always have adjustable vents near the bottom of the tent to let in fresh air. Some growers remove the covers completely, but that increases the chance the light will leak into the tent.

To get better airflow without light leaks, you can make a little “window” or light trap facing down (using the built-in intake vents) to let air through, but not light

4.) Connect Carbon Filter – No Smells!

Although some growers don’t use a carbon filter, that can unintentionally make a “smell trail” leading straight to their grow. Carbon filters ensure that no smells whatsoever escape to where they aren’t supposed to be. This provides peace of mind even if you aren’t worried about stealth. Plus some cannabis plants smell so hard the smell can get baked in your hair and on your clothes.

Just like the exhaust fan, I recommend hanging your carbon filter with rope ratchets because a carbon filter is surprisingly heavy, and rope ratchets make it easier to make adjustments.

It’s important that there is an air-tight line from the carbon filter to the fan (without any air leaks) in order to prevent smells from escaping the tent.

Growers often hang a carbon filter in the back of the tent so it’s less in the way.

Sometimes it makes more sense to tuck the carbon filter behind or above the grow light.

If you have an air-cooled hood you connect the carbon filter > light > exhaust fan. This is considered a “complete” exhaust system because it cools the grow light and scrubs all smells in one fell swoop while keeping everything completely inside the tent. Notice how the carbon filter is tucked behind the light and connected to the grow light with ducting.

If you don’t have space in your grow tent (for example you’re grow tent isn’t very tall), you can put the carbon filter at the “end” of your exhaust and sit it on top of your grow tent. This isn’t quite as effective as keeping the carbon filter in the grow tent, but as long as you don’t have any holes in your ducting or other ways for air to leak out besides through the carbon filter, it gets the job done.

Put the carbon filter after the fan on top of your tent if starved for space inside the tent. Note: This configuration gives you the most space inside tent, but is often louder since fan is outside tent. It’s very important to have a tight seal at the outlet, or the fan won’t effectively pull air out of the tent and through the filter.

Alternatively, hang the fan in the port, and use ducting to connect to the carbon filter on top. Note: Quieter than above option, but can be a bit less effective at smell filtering, since the air doesn’t push as strongly through the filter.

Remember: Carbon filter must be at ends (either the beginning or end of the line). If you put it in the middle, it doesn’t work!

No matter how you end up doing it, the main idea is to ensure any air leaving the tent must pass through this carbon filter and then have no air leaks or holes in the venting until the air is completely out the tent.

As long as you keep the tent closed and the fan on, you should never be able to smell cannabis in your home or outside. The negative air pressure caused by the sealed tent prevents any air inside the tent from leaking out.

Note: When you open the door of the tent it breaks this seal, which means smells may flood out the door or get pulled into the exhaust fan prematurely. To deal with smells when you open the tent, you can use a product called ONA gel, which is surprisingly effective at covering up odors on a short-term basis. However, if you put one of these inside your grow tent, the smell will get on your buds, so only use this as a “spot treatment” and not your main way to cover up cannabis smells..

Also, here’s a trick I learned from a dispensary owner: set up a carbon filter with a fan attached inside the room itself (in addition to the one in your tent), and run it alongside some ONA gel whenever you need to make sure all smells are gone quickly in the room, even if you’ve opened the tent. It works to keep a dispensary smelling neutral and it works just as well in the home!

If you have a smell emergency, you can use an exhaust fan directly attached to a carbon filter sitting on the floor. This isn’t as effective as a “real” exhaust system, but it will clear an entire room of smells in just minutes. Some growers who can’t fit a carbon filter in their grow space have even used this technique to control smells for a whole grow!

5.) Sound, Stealth, and Safety Check

You’re at the home stretch! Your grow tent should already be set up, and now it’s just a matter of double-checking everything and adding your plants!

Sound Check

You can dramatically reduce the sound of fans by hanging them as opposed to letting them sit on something. Keeping fans clean will also make them as efficient as possible while preventing sounds from developing.

For both air and water pumps, it makes a difference to place them on something besides directly on the ground. For example placing them on a piece of wood will muffle the vibration.

Light & Smell Check

You want to make sure no light or smells will make it outside the tent!

After everything is set up, turn on your grow light and exhaust fan for a day to test out your new space.

• The sides of the tent should bow inward slightly when you turn on the fan. Inward bowing means you have created negative air pressure, which is perfect because it will prevent smells from leaking into the home as long as the tent is kept closed.
• Ensure that your carbon filter is securely attached to your exhaust fan, with no way for air to leak in or out. A strong seal between the carbon filter and the fan will ensure that any air leaving the tent passes through the carbon filter first, which will completely scrub it of any smells.
• Take a minute to check around your house to see if you can hear anything that seems odd when your equipment is on. A constant hum or rattle can be suspicious, so listen carefully.
• Go outside and walk around your house once in the morning, once in the afternoon, and once at night to see if there’s any noticeable sounds or if you can see suspicous looking light from outside.

Safety Check

Lastly, take a good look around inside the tent. Everything should be secure. Make sure that any electronics are off the ground (power strips, ballasts, wires) just in case there’s ever a water spill.

A good rule of thumb is to keep all electronics above the waist, while anything to do with water is kept below the waist. Don’t leave cords hanging around in the tent. It’s not only safer, but it looks a lot nicer when you wrap cords up neatly and secure them in place 🙂

Learn more about electrical safety!

Get Started Growing! You Are Ready!

Now that you’re all set up, the major work is over! Here’s a very quick summary of what’s next:

1. Add container with growing media (soil, coco coir, hydroponics)
2. Add seeds
3. Give nutrients and water regularly
4. When plants are about 6 weeks old, put your grow lights on a timer so they turn off for 12 hours each day. Buds will start growing in 1-2 weeks.
5. Harvest sweet, sweet buds a few months later!

Get step-by-step instructions for the rest of your marijuana grow or read the 10-minute beginner’s guide to growing cannabis!

The post Complete Guide to Grow Tents for Cannabis appeared first on Grow Weed Easy.

Examples of Common Cannabis Growing Setups

This page will lead you to some setup shopping lists for a handful of the most popular styles of growing cannabis. You can use the information below to help decide which type of lighting you want to use if you don’t already know. The type of lighting you use will steer you towards some guides that will show you everything that’s needed to get started growing potent homegrown cannabis. You’ll get the initial setup cost, the cost to reach your first harvest (the highest cost), and the cost of subsequent harvests (much cheaper after the first).

2’x2′ Grow Tent – Small

• Ultra short edition – 3′ tall
  • 65W – HLG 65 LED Grow Light
  • 1-3 oz per harvest
  • $300 to get started
• Room to grow – 4′ tall
  • 100W – SF-1000 LED Grow Light
  • 2-4 oz per harvest
  • $430 to get started

Example of a 2’x2′ grow tent with 100W LED Grow Light (up to 4 oz)

2’x4′ Grow Tent – Medium

• Standard Power – 5′ tall
  • 200W – SF-2000 LED grow light
  • 5-11 oz per harvest
  • $555 to get started
• Max Power – 6′ tall
  • 300W – Mars Hydro TSL2000 LED 
  • 7-13 oz per harvest
  • $575 to get started
• Over Power – 6′ tall
  • 300-400W range (dimmable) – for growers who go crazy with power
  • Up to 16 oz per harvest
  • $495 to get started with a 400W HPS
  • $745 to get started with 315 LEC
  • $890 to get started with HLG 350R (Massively overpowered LED)

Here’s my current grow inside one of these right now. I think this is the perfect size for most home growers because it can yield many ounces up to a pound per harvest depending on the grow light you use.

200W LED grow light by Spider Farmer (up to 11 oz – see the grow journal)

3’x3′ Grow Tent (Square shape is better in some spaces) – Medium

• Max Power – 6′ tall
  • 300W – Mars Hydro FC-E3000
  • 7-13 oz per harvest
  • $475 to get started with FC-E3000
• Max Power (cold grow room) – 6′ tall
  • 315 LEC or 400W HPS (dimmable)
  • 7-16 oz per harvest
  • $745 to get started with 315 LEC
  • $495 to get started with a 400W HPS

Example of a single hydro plant growing in a 3’x3′ grow tent with a 400W HPS. You could fit more plants if you use pots instead of hydro

Mars Hydro has a remarkably cheap yet effective new 300W LED (harvest up to 13 oz) for a 3’x3′ released in 2025

4’x4′ Grow Tent – Large

• 1+ lb LED Producer – 6.5′ tall
  • HLG Blackbird 600W LED grow light
  • 11-22 oz per harvest
  • $995 to get started
• 1+ lb HPS Producer 6.5′ tall
  • 600W HPS (dimmable)
  • 10-21 oz per harvest
  • $495 to get started

Example of a 4’x4′ grow tent (easily yield a pound – see the grow journal)

Now that you’ve got an overview, let’s look at each of the cannabis grow kits a little closer.

Example Setups for Different Lighting Types

65W LED Mini Tent

Average Yield: 1-3 oz Per Harvest

Initial Setup Cost: $300

100W LED Grow Light in Mini Tent

Average Yield: 2-4 oz per Harvest

Initial Setup Cost: $430 to get started

200W LED (Only need 5 feet of height)

Can fit in some closets

Average Yield: 5-11 oz Per Harvest

Initial Setup Cost: $555 to start

300W LED Setup

Average Yield: 7-13 oz Per Harvest

Cost: $575 to Start

315W LEC Grow Light

Average Yield: 7-13 oz per Harvest

Cost: $745 to Start

350W LED Setup

Average Yield: 8-14 oz Per Harvest

Cost: $700 to Start

400W MH/HPS

Average Yield: 7-14 oz Per Harvest

Cost: $495 to start

600W MH/HPS Grow Setup

Average Yield: 10-21 oz Per Harvest

Cost: $495 to start

600W Premium LED Grow Light Setup

Average Yield: 10-22 oz per Harvest

Cost: $995 to start

Although there are larger size grow lights available (1000W and beyond), at that size it starts going outside the scope of a “hobbyist” grower as far as ease and yields. Also, I’ve found it’s typically better to have multiple 300W or 600W lights than one enormous grow light

Learn the basics of growing weed: Beginner’s Guide

These Cannabis Growing Setup Examples Assume You’re Starting From Scratch and Don’t Plan to DIY Anything

I tried to include everything in these lists, as if someone were growing marijuana completely from scratch. For each example I calculated the cost as if you were buying everything online off of Amazon.com from the included links. A lot of these items cost less money if you shop around online or buy them in person, and you may already have some stuff lying around the house already.

For each example I also included a matching grow tent, because I believe grow tents are the best way to create a perfect environment for your plant at a really low cost. But if you want to skip the tent and make your own grow space in a grow box or closet, learn how to create the perfect growing environment for your plants!

2 healthy, manifolded plants under a 600W MH (Metal Halide)

Over the years we’ve had lots of people request “starter” shopping lists for new growers – it can be frustrating trying to figure out exactly what supplies you need to start growing cannabis indoors! So today I decided to make a few comprehensive shopping lists for common setups that include everything from nutrients to grow lights to rope ratchets. I’ll even tell you what yields, electricity cost and cost/ounce to expect with each setup.

If you don’t want to have to figure out exactly what to buy to start growing, this article is for you! I will break down what to expect based on your space limits and desired yields, so you can get the exact perfect setup for your situation.

I need more/different help! Take me to the 10-Step Quick Start Grow Guide

Don’t Forget to Budget Money for Growing Medium and Plant Containers!

Remember to consider the growing medium (not included in totals). Here’s my very general estimate for 1-2 plants (you will need more to grow more plants). So consider you will need to spend an extra $30-125 for your growing medium + the cost of your container.

Choose One:

• Super Soil $40 (for 10 gallons of super soil) + container
  https://www.growweedeasy.com/super-soil
• Soil $30 (for 10 gallons Happy Frog soil) + container
  https://www.growweedeasy.com/soil
• Coco Coir $30 (for 2x coco bricks + perlite for 10 gallons) + container
  https://www.growweedeasy.com/coco
• Hydroponics $150 (to make reservoir)
  https://www.growweedeasy.com/hydro

Compare different growing mediums for growing cannabis

Learn the basics of growing cannabis!

Jump to…

10-Step Quick Start Guide to Growing

How Long Does it Take to Grow Cannabis?

Where do I get seeds?

Check These 7 Things & Cure 99% of Marijuana Growing Problems

The post Complete Cannabis Grower’s Shopping List Examples appeared first on Grow Weed Easy.

Table of Contents

1. Supplements That Protect Against Heat Damage
2. Environment Hacks
3. Optimize Your Grow Light
4. Change Your Light Schedule
5. Heat Resistant Strains

Are your indoor cannabis plants stressed out by the heat? Controlling heat in the grow room is one aspect of growing marijuana indoors that can be difficult for many of us growers. Grow lights provide our plants with lots of life-giving light, but they also get hot, and big grow lights (even some LEDs) can raise the temperature of a room by several degrees.

Quick Heat Stress Tip: Of course, the best thing you can do is control the heat. But if that’s not possible, sea kelp extract can help cannabis plants deal with heat and quickly recover from heat stress (use at 1 tsp/gallon).

Each cannabis strain is a little different and some plants can handle hotter temperatures than others, but most plants start suffering from heat stress when their temperature gets over 85°F / 30°C.

Temperatures above 85°F / 30°C often causes problems, but if it’s not too severe plants may still grow slowly.

Some sensitive cannabis strains from cold climates (most often the short, squat, Indica strains with huge leaves) may start showing heat stress if the temperature rises above 80°F / 27°C. To avoid heat stress, you must keep your grow space below a particular plant’s comfort threshold.

Too much heat, especially over time, can greatly harm or even kill your cannabis plants.

But it’s not just plant growth that benefits from ideal temperatures. Controlling the temperature in the flowering stage has immense benefits to bud quality.

Buds that develop in a good environment reward you with increased density, terpene levels, and overall THC levels/potency.

On the flip side, too much heat harms bud development in the flowering stage by burning off smell/potency, discoloring buds, and causing buds to grow loose or airy.

Developing in heat can make buds look “ugly”.

Heat or light stress can cause a plant to keep making new growth on the parts of the buds that are closest to the light. When you see these top-heavy oddly-shaped “fist” buds, it’s usually the result of heat and/or light stress.

What can you do to protect your cannabis plants from heat damage?

This tutorial will teach you tactics that you can use to control temperature and fix heat problems to produce a plant paradise. You also get tips to help your cannabis plants thrive even if the grow space is getting too hot.

This tutorial shows you how to deal with heat so you grow healthy plants with beautiful potent top-shelf buds.

1.) Supplements That Protect Against Heat Damage

Some supplements can help protect your cannabis plants so they are more resistant and/or recover more quickly from heat stress.

However, many different companies offer supplements and it can be confusing to decide which one – if any – is best for your garden.

Try to get supplements and nutrients from the same company

For the most part, there is no best supplement for heat (or anything really). A lot of different supplements will get you to the same place in the end. Because of that, when possible it’s a good idea to choose supplements made by the same company as your nutrients instead of trying to find the “best” supplement.

This is because during the process of creating a complete nutrient lineup, nutrient companies specifically test their supplements to make sure they work together with the nutrients in their lineup nutrients without causing lockout or other unexpected problems.

So if you’re using the General Hydroponics Flora Trio nutrients, for example, it’s much safer for your plants to add supplements by General Hydroponics if possible. If you were using Botanicare nutrients you’d look at the supplements that Botanicare carries, etc. Learn about different types of nutrients for growing cannabis.

Use supplements to help protect your plants from heat damage if temperatures are rising too high

Seaweed Kelp Extract

One of the best inoculants against heat stress is a surprising gift from the ocean; seaweed! As a bonus it contains small amounts of trace nutrients and minerals. Many different nutrient companies use seaweed kelp extract as part of their supplement lineup, which means you have a lot of choices to choose from if you want to incorporate seaweed into your grow.

A few companies offer seaweed extract by itself, like organic Bloom City Liquid Seaweed. Liquid Kelp is a lovely choice for those growing outdoors or in super soil as they contribute to a healthy soil web matrix. Suitable for soil growers who want to avoid using mineral-based nutrients, but can also be used in coco or hydro (just make sure it doesn’t clog any nozzles).

Pure sea kelp extract is a great organic heat stress supplement. Use at 1 tsp/gallon.

If your nutrient company doesn’t offer a specific Sea Kelp product, you can almost always find sea kelp extract as an ingredient in one or many of their supplements. For example, General Hydroponics has a great all-in-one supplement called Floralicious Plus that contains several ingredients that work together to not only protect your plant against heat with seaweed extract, but can help it to produce better in other situations, too.

Or if you’re growing with Fox Farms nutrients, their Kelp Me Kelp You supplement not only has seaweed but also other ingredients that can make cannabis plants more hardy. So a great marijuana supplement for heat stress.

When starting out with supplements, it’s often best to start with something that matches your base nutrients and has sea kelp extract as an ingredient, like Floralicious Plus by General Hydroponics.

Silica Supplement

Supplementing your plants with extra silica (listed on the label of supplements as Potassium silicate) is not usually needed for healthy plant growth. There is almost always some amount of silica available, and plants don’t need a whole lot of silica to survive.

That means if your plants aren’t stricken with a (super rare) silica deficiency and are living in a great environment, adding extra silica might not give you tangible benefits. However, if your cannabis plants are under specific types of stress or are generally living in adverse conditions, extra silica can make life easier for your plant.

Silica (listed as Potassium silicate ) helps make plants more resistant to heat. Examples: General Hydroponics Armor Si and Dyna-Gro Pro-Tekt. It’s especially helpful to give extra Silica while your plants are still growing stems and leaves, as the silica gets incorporated into the cell walls.

The most popular silica supplement for marijuana plants may be Bloom City Silica Boost. (Use at 1 tsp/gallon, stop several weeks before harvest)

Plant roots with access to silica (Si) happily drink it up and the silica gets incorporated into plant cells, increasing the strength of individual cell walls. These “armored” cells help improve the hardiness, vigor, and structure of the plant. Kind of like sending your plants to the gym.

Benefits of Silica Supplements

• Plants supplemented with silica are generally more resistant to heat or cold stress as well as some types of disease.
• Silica increases the microscopic “abrasiveness” of leaves, which can act as a deterrent to pests and herbivores (like deer). In fact, if you’ve ever been given a paper cut by a piece of grass, you can thank silica for making those “sharp” edges.
• Silica helps plants get the nutrients they need. Silica is effective at making phosphorus more available to the plant, which can be helpful in the flowering stage when the plant is going through phosphorus at a much higher rate due to the process of making buds.
• Silica can also help the plant roots better absorb micronutrients (including boron, copper, iron, manganese and zinc) while making it harder for the plant to absorb certain toxic substances like aluminum and salt/sodium.

So again, silica won’t magically increase your plant growth, but it can help make up for some problems with the environment. Because of this, nearly all professional nutrient companies carry a quality silica supplement as part of their lineup.

I like Armor Si by General Hydroponics, but again that’s because they make my base nutrients. There is a silica supplement available from almost every major nutrient company out there and you’re least likely to run into problems if you go with the company that matches your nutrients.

Armor Si by General Hydroponics is an excellent silica supplement, especially if the rest of your nutrients are from General Hydroponics.

Note: Silica supplements (or more specifically, their main ingredient Potassium silicate) will raise the pH of your water, so you may need to use a little bit extra PH Down. Learn more about pH.

Root Health Supplement (Essential for Hydroponic Growing in Heat)

Not only does heat bother your plants above ground, but the roots may also become diseased. When growing cannabis hydroponically (and to a lesser extent when growing in soil or coco) it’s very easy for your roots to start running into problems like root rot when the temperature starts getting too high.

Cannabis plants in hydroponic systems are prone to root rot if you don’t give them a root supplement. Especially if it’s hot!

Full Tutorial – How to Get Rid of Root Rot

The types of microorganisms that attack roots thrive in hot, wet conditions without much oxygen. Unfortunately, in hydroponics your water can’t hold as much dissolved oxygen when it’s hot, and dissolved oxygen is one of the best ways to fight off root disease.

So it’s sort of a double-whammy for plants grown hydroponically when it gets too hot in the grow room: they’re getting less oxygen AND becoming more vulnerable to root rot.

Besides using an air pump with large air stones to create lots of bubbles in your reservoir (learn more about growing cannabis hydroponically), the best thing you can do to keep roots healthy is control the heat.

Unfortunately, as you know, controlling the heat is often easier said than done.

There are some products that are made up of beneficial bacteria and other microorganisms that specifically fight root rot. These work by out-competing the bad microorganisms in your water reservoir and populating your reservoir with friendly ones that actually help your roots.

Drooping is often the first sign your plants are suffering from root rot

Plants with root rot may also start getting what looks like various nutrient deficiencies, but the true cause is actually the unhealthy roots

My product of choice for fighting root rot is Hydroguard by Botanicare. Normally I only use nutrients and supplements by General Hydroponics but in my experience, this product has been the best for fighting root rot in DWC / hydro, so I use it specifically. I’m definitely not saying it’s the best root supplement out there, but it’s the best one I’ve ever used and I want to recommend something I know for sure will work. It doesn’t change the pH of the water, and it doesn’t interact with other supplements. I’ve seen it actually fight root rot directly, even when it’s hot, and I never go a grow without it.

I highly recommend Hydroguard as a root supplement for any hydroponic grower struggling with heat or root rot

I’ll be honest, I grow hydroponically in San Diego, and my grow room is too hot during the summer. I used to suffer from root rot but as long as I use 1 teaspoon per gallon of this supplement in my reservoir, I see white, healthy roots even in the heat.

I realize this isn’t a direct method to combat heat; rather, it’s a way to help deal with the consequences of too-high heat when it can’t be controlled. It’s best to control the heat in your grow area, but if that’s impossible Hydroguard will help keep your roots healthy in DWC / Hydro! It’s cheap and a little bit goes a long way. A 1-quart bottle will last you more than one grow!

2.) Environment Hacks

Add CO2 to the Air

Plants can easily survive in temps up to 95°F (35°C) when the air is being supplemented with extra CO2. However, for CO2 to make a difference to your plants, you need relatively strong grow lights (i.e. HPS, LEC, or big LEDs). But for those with strong grow lights, adding extra CO2 can result in faster growth as well as making it so plants can better handle the heat.

Learn how to add CO2 to your grow

Choose Soil or Coco (Hand-Watered Grow) Over DWC/Hydro

Growing cannabis hydroponically can give you some of the fastest growth rates of any style of growing, but as mentioned earlier, hydro does not really play well with hot temperatures because too much heat tends to trigger root problems and slower growth.

We talked about supplements that help prevent root rot for hydroponic plants, but the next step is to cut out the water reservoir altogether and go for a hand-watered grow. That’s because hand-watered plants are inherently much more resistant to high temperatures. Not only are the roots relatively safe from the heat (unlike in hydro) but the growing medium can hold a lot of oxygen no matter what the temperature (a lack of oxygen at the roots causes major problems in hydro).

Plants grown in containers or in the ground tend to be more resistant to heat compared to hydro.

Soil in regular containers is probably the most common way to grow cannabis indoors, and that combo works great.

But when it comes to growing in hot temps, coco coir may be a better choice than soil. In particular, coco coir inherently has properties and hormones that encourage healthy root growth and promote hardiness against heat.

Soil is a good choice, but coco coir is even better when it comes to heat.

Use Smart Pots or Air Pots (instead of hard-sided pots) 

Choose a Smart Pot (fabric pot) or Air Pruning Pot (plastic pot covered in holes) to let air in and help cannabis plants with the heat. These pots help increase evaporation from the sides of the root ball, which not only reduces the chance of overwatering but also helps keep roots healthy and heat-resistant by providing plenty of oxygen from the sides.

Use Smart Pots (fabric pots) instead of regular containers as further protection against heat. These coco-grown plants were regularly exposed to temps that crept up over 85°F (30°C), and although that wasn’t ideal they made it to harvest just fine.

Air pruning pots are plastic but have holes in the sides, which accomplishes the same thing as fabric pots (gets more air to the roots) and makes them more heat-resistant.

Growing cannabis with coco coir in fabric pots is one of the best ways to grow if you want your plants to be able to resist the heat.

Keep Roots Cool

Your plant is much more resistant to heat if the roots don’t cook too, whether you’re growing in a pot or in a hydroponic reservoir. If you can find a way to help keep the roots around 70°F (21°C), your plant will suffer less and recover more quickly from a hot spell.

Watering your plant regularly when it’s hot will keep roots from drying out and help them stay cool. If the sides of the pots are getting hot from the grow light, put your potted plant inside a bigger pot (or find some other way to block the pot from direct light. This can help keep roots significantly cooler.

If the sides of pots are getting hot from the light, put the whole plant in a bigger pot to create an air gap and keep the roots out of direct light

Use Fan Placement to Reduce Electricity & Bring Down Temps

Air conditioners can easily control the heat in any room but they use a lot of electricity, which can get expensive really fast! Unfortunately, a lot of growers are using an AC (or just dealing with too much heat) when they could actually reconfigure their fans to be able to maintain the right temps without needing an AC at all.

Proper fan placement can also help save costs because if you use fans more effectively you can use less of them. A lot of fans can use a surprising amount of energy that can really add up over time. That means you don’t want to fill your grow space with tons of fans if you don’t need to.

Being smart about fan placement and investing in electrically efficient fans can save you a lot of money. 

Exhaust Fans

The most effective way to control heat is to use an exhaust fan to vent hot air out of the grow space. Make sure your exhaust fan is set up to make sure you have the most cooling power. Here are some tips:

• Grow space is mostly sealed – Your grow space should be mostly sealed for an effective exhaust system, with just ports for air to come in near the bottom of the grow space, and a port for your exhaust fan to blow air out from near the top of the grow space. I highly recommend getting a grow tent for smaller grows to make this super cheap and easy. A grow tent with a strong exhaust fan creates a breezy plant environment that may not even need many other fans. As an added bonus, a grow tent makes it easy to control smells with a carbon filter so no one can smell your plants even in the same room.
• Strong exhaust fan – Your exhaust fan should be strong enough for the size of your space or tent. Avoid cheap ducting fans as they don’t move enough air to cool your grow light. Learn more about choosing the right exhaust fan.
• Vent air from top of grow space – Heat rises to the top of your grow tent/area, so make sure your exhaust fan is located at the top of the tent pointing out.
• Intake holes – You want holes to intake air, about 4x the size of your exhaust hole if possible. When the intake hole is too small it’s hard on your fan, the exhaust won’t be able to vent as much hot air. With grow tents, the intake ports are already built-in so you just leave them open so air can get through.
• Input fresh, cool air – The intake hole should have direct access to cool, fresh air. The inside of the grow space is always going to be at least a few degrees above the temperature of the intake air, so if the intake air isn’t cool the grow space will be even hotter. Cool air stays lower to the ground, so make sure your intake ports are as close to the floor as possible.

Learn more about setting up exhaust system.

Ducting

Keep all ducting as straight and short as possible. You want a short direct line to the window so that hot air is immediately vented outside. Try to avoid using anything in the window that restricts airflow. Though it’s often necessary to use some type of screen to make sure no one can see in, try to do the best you can to obstruct airflow as little as possible. How can I set up an exhaust that looks normal from outside?

Try to keep any ducting as short and straight as possible.

Window Fan

It may seem simple, but a window fan can be surprisingly effective at venting some of the heat if the grow light is raising the overall temperature of your room. In some cases, a window fan can cool your room by several degrees, which can help keep your plants cool. I sometimes call this a “No-Ducting Exhaust” but honestly it’s more like a ‘poor man’s exhaust’ if this is the only thing you’re doing to vent out heat. But that doesn’t mean it doesn’t help,

If grow lights are raising the temperature of your room, a window fan can help vent heat and cool the room down by a few degrees

In order for a window fan to cool a room most effectively, there needs to be some sort of “intake” for cool air to get in. It’s like a bigger version of an exhaust system. A separate open window in the same room is perfect, though an open door can also help, especially if there’s an open window somewhere in the house. However, even in a completely closed room, a window fan can help keep temps down somewhat in the room because it helps vent out heat from the grow light. Although blowing air out is often the most effective, if the air outside is really cool sometimes it helps to blow air in. Experimentation is good.

Clip-On Fans

Small fans help ensure there is a gentle breeze around your plants and buds. This helps plants grow faster, helps buds develop more dense/tight, and reduces the chance of issues like white powdery mildew or bud rot.

Some specialty clip-on-fans are designed specifically to attach to the poles of a grow tent.

Oscillating Fans

Oscillating fans are perfect for reducing “hot spots” that form in the grow space. Certain grow lights can cause major hot spots. If it’s most hot directly under the light, using fans to blow that heat away from your plants can make a huge difference in how much heat they experience.

In addition to oscillating fans, using a strong-enough exhaust fan with a big intake hole helps keep everything moving so hot spots don’t form. In fact, a smallish grow tent with a good exhaust fan may not even need extra fans because the exhaust fan itself will make the entire tent breezy.

Just be aware that adding oscillating fans doesn’t bring down the overall temperature in the tent. Fans only move air around. So if the entire grow space is already hot, adding more fans isn’t going to help.

Learn more about how to effectively set up oscillating fans in the grow room.

3.) Optimize Your Grow Light 

There are several ways you can optimize your grow lights, up to and including upgrading to better ones.

Get the Right Size Grow Light (a smaller grow light doesn’t necessarily mean lower yields!)

Grow lights that are optimized for your size grow space tend to reduce problems with heat. Too much heat hurts yields by making plants grow poorly. On top of that, too much light (light stress) can prevent buds from fattening and make plants more sensitive to heat.  That means having the right size light for your space will help prevent the space from overheating. When buying a grow light, many manufacturers list which size space the particular grow light is optimized for (aka 2’x4′ or 4’x4′). Try to match the right size grow light to your space.

In some cases, getting a smaller light can actually increase yields, especially if the heat is out of control with your current light.

 If you’re struggling with heat and plants are constantly heat stressed, consider stepping down the light. These plants grew better after the grower turned down the power.

These plants were also getting way too hot. The grower started getting better yields when they took one of the LED panels out of the space.

Side note: I’ve found that older and “blurple” colored LED lights tend to put out far more heat than modern LED panels. Buds also don’t fatten as well under them.

Avoid blurple LEDs for growing weed!

Use an LED Grow Light

When it comes to heat control, LEDs are hands-down the best cannabis grow light. As of 2025, multiple newer LED grow lights have proven to be incredible at growing cannabis. These modern LEDs have been developed using real cannabis plants and live up to the LED hype, producing amazing yields and beautiful bud quality.

In my experience, nearly all newer LEDs run cooler per watt than other grow lights like HPS, or CMH/LEC.

On top of the fact that LEDs produce less heat compared to other lights, cannabis plants under LEDs typically can stand higher temperatures. So LEDs give you a light that puts off less heat and plants that can stand more heat. If heat is a concern, you want to go with LEDs.

Note: LEDs perform poorly in the cold. If you deal with cold in the grow space, HPS or CMH/LEC may be a better choice since they produce more heat and plants can stand cooler temperatures under them.

There are a lot of LEDs to choose from and the sheer number of options can be overwhelming. If you’re interested in getting your first LED and aren’t sure which one to get, Spider Farmer brand LEDs are a good mix of quality and price. They get a good rate of growth in the vegetative stage and better yields/bud quality than many LEDs in the same price range. I recommend avoiding generic LEDs (like you would buy from Alibaba) because they usually get hotter than expected for the wattage and often produce poor yields or bud quality.

The Spider Farmer SF-2000 LED grow light uses 200W of electricity and produces relatively little heat.

In my most recent grow, the Spider Farmer SF-2000 produced over 10 oz in a 2’x4′ grow tent, or over 1.5 grams/watt. The plants grew quickly and well. I got the buds lab tested and it produced more terpenes and THC than the other LEDs I tested at the same time. A great choice for under $200.

My friend used the Spider Farmer SF-1000 (100W and costs $90) in a 2’x2′ grow tent and produced several ounces. This light can be kept 8″ (20 cm) away or even closer for some plants, which makes it effective for small spaces.

Learn about other popular LED companies for growing cannabis.

Reduce Power

Many LEDs and other types of grow lights are “dimmable” which means they have different power settings that allow you to reduce the power of your light. For example, you might be able to set your grow light to 75% or 50% power. In these modes, your grow light will use less power and give off less light/heat. If there’s a heat wave coming up, it might be helpful to turn down the power until things cool down.

Raise Grow Lights

Raising your lights tends to help bring down the temperature experienced by the plants, especially with big fluorescent lights, CMH/LEC, and MH/HPS grow lights. Getting a lot of light can make plants more likely to suffer from heat, so another bonus of moving your lights further away can help them be more heat-resistant.

Note: If I need to raise my grow light higher than the normal hanger allows, I use zip ties to attach the grow light to the top of the tent. However, make sure to leave at least a little air gap so you don’t have a hot lamp touching the top surface of the tent directly (this can be a fire hazard).

Raise grow lights (if possible) when the plants are getting too hot to help reduce the heat they experience and especially reduce heat on developing buds. Sometimes a few inches can make a difference.

Learn more about how far away to keep grow lights from your plants.

4.) Change Your Light Schedule

Opt for 18/6 Light Schedule in the Vegetative Stage

Many growers give their plants 24 hours of light a day in the vegetative stage to produce the fastest growth. Yet turning the grow light off for several hours each day helps keep the temperature down, especially if lights go off during the hottest part of the day. The 18/6 light schedule is suitable for all plants in the vegetative stage, and for auto-flowering strains from seed to harvest.

Plug your grow light in an electrical timer to control the light schedule

Side Note: Although plants do grow faster if they’re getting 24 hours of light a day, you get diminishing returns after 18 hours of light a day. Cannabis plants benefit from having a night stage, and that helps make up for the lack of extra light. The difference in growth between 18/6 and 24/0 isn’t very noticeable (the increase in growth may not justify the extra electricity and heat).

Learn more about cannabis light schedules here.

Set Your Dark Period for the Hottest Part of the Day

This is a super simple solution to help control the heat for growers who get high temperatures in the middle of the day. User your timer to set your “Off” time to happen during the hottest hours of the day and you’re done. As long as you make sure plants don’t get light during their dark period, they won’t realize their “day” is during your night.

5.) Start with a Heat-Resistant Strain

Some strains are inherently more resistant to heat than others. For example, strains that originated from the equatorial region, including many Sativa and Haze strains, can resist much higher temperatures than strains that originated in colder regions, such as many Indica strains.

• Tall strains with thin leaves tend to be relatively heat-resistant
• Short, bushy strains with fat leaves tend to be more sensitive to heat
• Check the strain description to see if it mentions anything about temperature

Here are some strains that are heat resistant, easy to grow, and produce great effects.

Photoperiod (Traditional) Strains

White Widow

• Legendary strain
• Buds produce smooth relaxing effects that are great for enjoying with friends
• Overall easy-to-grow and resistant to heat and mold
• Has a surprisingly short flowering stage (8-9 weeks) for a Sativa-dominant strain, and doesn’t get too tall
• Great yields even if you mess up a little
• Get White Widow from Seed Supreme (ships from USA)

White Widow is a legend!

Purple Thai

• Thrives in higher heat and humidity than most strains
• Grows tall and stretchy so you need to train the plant to reduce the height (or it may grow into your light)
• Pretty potent at 22% THC but still more of a “head high” (it may even be suitable for day use for high-tolerance people)
• Get Purple Thai from Seed Supreme

Purple Thai laughs in the face of heat!

Afghan

• In addition to doing well in the heat, this strain is overall easy-to-grow and resistant to pests and mold
• Buds produce very heavy effects (a “brain melter”)
• Great yields and bud quality
• Get these Afghan genetics.

This Afghan plant thrived in burning hot temperatures during a heat wave.

Sour Diesel

• Withstands heat and light better than most strains I’ve grown
• Strong fast plants that tend to be stretchy/tall (not the best choice for small spaces)
• Buds are consistently potent and high quality
• Takes 12 weeks in the flowering stage but rewards with huge yields
• Get these Sour Diesel genetics.

Sour Diesel is the plant on the left. It produced over 9 ounces on one plant.

This bud from that Sour Diesel plant grew within 8″ (20cm) of a 600W grow light in the middle of a heatwave. The plant on the right suffered tons of damage despite being further away. On the other hand, the Sour Diesel buds came out huge and potent with a little heat foxtailing on top buds that were closest to the grow light.

Auto-Flowering Strains

The Ruderalis hemp ancestor of all auto-flowering strains originated in the frigid cold climate of northern Siberia. These plant’s developed the auto-flowering trait so they could complete their whole life cycle during 2-month Arctic summer. Unlike photoperiod plants, these plants didn’t have the luxury to wait until the sun told them winter was coming. They had to complete their whole life as fast as possible. As a result of the cold climate of their ancestors, auto-flowering strains tend to be sensitive to heat. However, some breeders have bred out the trait by crossing with heat-tolerant strains. The following is an example of a heat-resistant auto-flowering strain that also produces great buds.

Amnesia Kush Auto

• Gets a bit tall, but usually not too bad since it’s an autoflowering strain
• Excellent “day” buds with a pleasant mental buzz
• Get Amnesia Kush Auto from Seed Supreme (ships from USA)

Get Amnesia Kush Auto for your garden!

Auto Blackberry Kush

• Beginner-friendly
• Resistant to heat as well as plant stress in general
• Incredible fruity smell
• “Body stone” that keeps you glued to the couch
• Get these Auto Blackberry Kush genetics.

An Auto Blackberry Kush plant in a DIY setup

Dos Si Dos Auto

• Easy to grow (can handle some mistakes)
• Smooth, relaxing effects
• Above-average yields
• Buds smell of citrus with hints of cake or cookies
• Get these Dos Si Dos Auto genetics

Dos Si Dos auto by Barney’s Farm is known for its yields, bud quality, and fast growth.

If you have experience with a great heat-resistant cannabis strain, please contact us!

Most importantly, take extra good care of heat-stressed plants – try to baby them as best you can!

Jump to…

Growing Cannabis with Super Soil

How to Use Coco Coir as a Growing Medium

Top-Fed DWC (Bubbleponics) Tutorial

How do I produce top-shelf buds every time?

Where can I get seeds?

The post 5 Secrets to Controlling Heat Indoors appeared first on Grow Weed Easy.

Hands-down the best way to control the smell of your growing cannabis plants is to use a carbon filter (learn more about different options for covering up cannabis growing smells). When installed correctly as part of an exhaust system, a carbon filter will not only prevent the smell of cannabis from leaking outside, but it will also prevent it from smelling up your home. A carbon filter can be more effective than any other method for controlling smells, and it won't alter the smell of your cannabis.

A carbon scrubber can completely hide the smell of growing cannabis plants, even really smelly ones!

A carbon filter is usually shaped like an enormous tube, and they're usually pretty heavy. The way they work is they are filled with carbon inside. When air passes through the carbon it neutralizes any smells, and when the air is passed out the back it is completely odor-free. However, for a carbon scrubber to work the air needs to be pulled through the filter, which is usually done using a strong exhaust fan.

In the left pic the carbon filter has a sleeve to help keep out extra dust, while on the right is a "naked" carbon filter so you can see how air can pass through the sides.

When using a carbon filter, the way you set up your exhaust is important; if you don't set it up properly it won't work well, if at all!

Get a Carbon Filter on Amazon.com!

1.) To Prevent Smells From Leaking into the Grow Room

The exhaust fan needs to be strong enough to create a vacuum in the grow space (in a grow tent you'll see the side bowing in). That means that all the smelly air is getting vented out the tent so fast that the suction prevents any from going back into your room. Even without a carbon filter, if you have good suction you won't smell anything outside the tent!

Learn how to set up an efficient exhaust system
 

2.) To Prevent Smells From Leaking Outside

Once you have suction in the tent and you're venting all the smelly air outside, the next step is to "scrub" smells out of that air before it leaves the house. This is where the carbon filter comes in!

This is the most common way to set up a carbon filter:

Carbon Filter > Grow Light > Exhaust Fan > Outside

This simple diagram shows how many growers set up up their exhaust system

This is an example of a carbon filter in action

​

Get a Carbon Filter on Amazon.com!

As air is pulled in through the sides of the carbon filter it is scrubbed of all smells. That air then passes through the ducting, blows over the hot light, and the hot unscented air is then vented outside.

No air leaks in your exhaust system! It's important that the only way air can enter the system is through the carbon filter, and that air should go straight outside. If there are leaks in the ducting or around the grow light, then smelly air can escape that way instead of passing through the carbon filter first.

That's pretty much it! You now know the basis of how set up your own effective and efficient exhaust system so odors never escape again!

Get step-by-step instructions on how to set up your carbon filter with exhaust

Jump to…

7 Tips to Growing Top-Shelf Buds

How to Set Up Your Grow Lights – Step-By-Step Tutorial

Stealth Growing: How to NOT get Caught Growing Weed

How (and Where) To Get Marijuana Seeds in the USA (and around the world)

The post How to Use Carbon Filters for Cannabis appeared first on Grow Weed Easy.

In addition to the search bar, this link guide helps you navigate through the Grow Weed Easy website. Learn about growing topics you won’t find anywhere else! This is a shortened list of all our cannabis growing tutorials, as the website has over 500 articles and tutorials!

Full List of EVERYTHING on GWE  ← Over 500 Articles & Growing Tutorials!

Start Here – Beginner Grow Guides

• Complete Beginner’s Guide
• How do I start growing my own weed indoors? (get help choosing your setup)
• How to Grow Weed in 10 Steps
• Simplest Cannabis Grow Guide Ever!
• How Long Does It Take to Grow Weed? (Marijuana Growth Timeline)
• 3 Steps from Beginner to Legendary Grower
• Complete New Grower’s Shopping List

Cannabis Life Stages

• Germination
• Vegetative Stage (Getting Bigger)
• Flowering Stage (Making Buds)
• Harvest

Choosing…

• Best Type of Nutrients
• Choosing the Best Grow Light
• Soil vs Hydro
• How Many Plants Should I Grow?
• What Part of the House Should I Grow In?
• What Setup Should I Get?
• Best Strains for Beginners
• Where to Get Seeds (including the U.S.)

Common New Grower Topics

• How Much Will Electricity Cost?
• Stealth Growing: How NOT to Get Caught Growing Weed
• What Equipment Do I Need?
• Germinate Your Seeds
• 7 Things I Wish Someone Had Told Me When I First Started Growing Weed
• How to Save Money When Growing Weed
• How to Store Weed Properly (so it never loses smell or potency!)
• Ask Questions & Get Answers From Real Growers! (In Our Free Growing Community)
• Cannabis Grower’s Glossary

Problems & Symptoms

• Cannabis Problems Guide
  • How to Help Yellow Seedlings
  • How to Fix Yellow Cannabis Leaves
  • How to Fix Curling and Clawing Cannabis Leaves
  • What Causes Dry or Crispy Leaves?
  • What Causes Brown Spots on Cannabis Leaves?
  • What Causes Bananas (“Nanners”) on Cannabis Buds?
  • Is This Nutrient Burn on My Marijuana Plant?
  • What causes red stems in cannabis plants?
• Diagnose Your Sick Plant
• Bugs & Other Cannabis Pests
• How to Prevent Nutrient Deficiencies
  • Which Nutrient Deficiencies are Caused by pH? (picture guide)
  • How to Stop Flowering Stage Nutrient Deficiencies
• 7 Reasons Why Cannabis Plants Grow Slow
• 5-Step Remedy That Fixes 99% of Grow Problems
• All-Natural Pesticides – Safe Up to Harvest!

Plant Training (Indoor Tricks for Bigger Yields)

• Simplest Plant Training Guide Ever!
• How to Control Height of Indoor Cannabis Plants
• Complete Plant Training Guide
• Breakdown of Techniques​
  • Low Stress Training (LST) Tutorial
  • Topping vs FIMing Tutorial
  • LBH’s Famous ScrOG Tutorial
  • Supercropping: Magic Technique to Control Cannabis Plant Height
  • Sea of Green (SoG) Tutorial
  • 12-12 from Seed – Flowering Plants Early
  • Nebula’s Manifold Tutorial
  • How to Manifold Clones
  • Nebula’s Bud-Based Defoliation Tutorial
  • Alternate Defoliation Tutorial ​
  • What is Re-Vegging / Monstercropping?
• How Can I Train an Auto-Flowering Plant?
• 7 Unfortunate Plant Training Mistakes

Grow Mediums

• What’s the Best Growing Medium?
• Soil vs Coco vs Hydro
• Basic Soil Guide
• Organic Soil Compost Guide (Super Soil) – Just Add Water!
• Coco Coir Guide
  • Coco Coir: The Most Flexible Cannabis Grow Medium
• Hydro/DWC/Bubbleponics Guide
• “True” Organic Growing vs Just Using Organic Nutrients
• Can You Use Miracle-Gro?

Nutrients

• Which Nutrients Are Best For Growing Cannabis?
• Soil Nutrients
• Coco Coir Nutrients
• Hydroponic Nutrients

Grow Lights

• 5 Best LED Grow Lights 2025 (Yields, Speed, & Bud Quality)
• Compare Types of Cannabis Grow Lights
  • Fluorescents (T5s) – Good for Seedlings Only (not powerful enough to produce potent buds or big yields)
  • CFLs (Spiral Bulbs) – Not Recommended (LEDs are much better)
  • LED Grow Lights – Recommended for Most Home Growers
  • MH/HPS Grow Lights – Good Alternative to LEDs, But Run Much Hotter
  • CMH / LEC Grow Lights – Good Alternative to LEDs, But Run Much Hotter
  • Plasma / Magnetic Induction Grow Lights – Not Recommended (poor cannabis growth)
• How Does Light Spectrum Affect Marijuana Plants?
• How Far Away Do I Keep My Grow Lights?
• You Can Actually Give Plants Too Much Light?!
• Grow Light Upgrade Guide: Yields & Potency Explained
• Cannabis Grow Lights: What’s the Best Size?

Best LED Grow Light Articles

• 5 Best LED Grow Lights 2025 (Yields, Speed, & Bud Quality)
• LED Grow Lights: Too Much or Not Enough Light?
• LED Grow Journal: Mars Hydro TSL-2000W vs Spider Farmer SF-2000
• LEC vs LED Grow Lights: Side-by-Side Cannabis Grow Journal
• Nebula’s Auto-Flowering Grow Journal (Topping vs Natural) – cannabis plants are grown under LED grow lights

Environment

• Create the Perfect Growing Environment
  • Temperature Tutorial
  • 5 Secrets to Heat Control
  • Control Humidity for Better Buds
  • How to Use Reflective Walls to Increase Yields Indoors
  • How to Make Plants Grow Faster with CO2
• Where’s the Best Place in the House to Grow Your Plants?
• How to Control Odors
• How to Set Up an Exhaust
• How to Set Up a Grow Tent for Better Yields (and Stealth)

Plant Care Tutorials

• Cloning
  • How to clone weed in a cup of water (easy!)
  • How to make cannabis clones with an aero cloner
• Intro to Plant Training for Bigger Yields Indoors
• How Often to Water Plants
  • The Easiest Way to Water Plants & Remove Runoff
• How (and When) to Transplant Cannabis
• Male vs Female Plants
• When to Harvest?
• Drying & Curing

How to Improve…

• Yields
• Bud Quality
  • 7 Environment Effects on Bud Quality
  • The Secret to Excellent Bud Quality
• THC Levels
• CBD Levels
• Smell/Taste
• Density
• Bud Color (How to Grow Pink or Purple Buds)
• Glitter (Make Buds Sparkle with More Trichomes)
• Bonus: What Determines Yields?

Buying Seeds

• Where to Get Seeds
• How to Find the Right Strain
• What are “Feminized” Seeds?
• Which Breeders to Trust?
• Photoperiod vs Auto-Flowering Cannabis Strains
• Bag Seed vs Hype Seed: Is it worth it to buy cannabis seeds?

Recommended Strains

• Best Autoflowering Cannabis Strains for Yields & Potency
• List of Sugar-Dusted Strains (Heavy Trichome Genetics)
• 10 Cold-Resistant Cannabis Strains
• 14 Heat-Resistant Cannabis Strains
• Which cannabis strains stay short? (Best strains for small spaces)

Auto-Flowering Strains

• Nebula’s Guide to Cannabis Auto-Flowering Strains (Photoperiod vs Auto-Flowering)
• Should I “Top” or Train an Auto-Flowering Plant?
• What’s the best light schedule for auto-flowering strains?
• Nebula’s Auto-Flowering Grow Journal (Topping vs Natural)

Edibles

• Decarboxylation: How to Decarb Your Weed (crucial step for just about every edible recipe)
• Best Weed Butter Recipe
  • How to Make Great Brownies with Weed Butter
• Canna Caps
• How to Make Cannabis Gummies (Weed Gummy Bears)
• How to Make Cannabis Tinctures
• How to Make Hash Oil (aka Cannabis Extract Oil, Rick Simpson Oil, or RSO)

Extracts (No Solvents Used in Any Recipe)

• Solventless Extraction Showdown – Bubble Hash vs. Dry-Ice Hash!
• Dry Ice Hash (Made with Dry Ice)
• How to Make Bubble Hash (Made with Ice Water)
• How To Make Your Own Homemade Rosin (dabs)

And Lots More!

• How Long Does it Take to Grow Weed?
• Vegetative vs Flowering Stage (Long Days vs Long Nights)
• Germination & Seedling Mistakes
• Simple Guide to Plant Training
• What’s the Best Pot / Container?
• Perpetual Harvest
• What Determines Yields?
• 5 Time-Savers for Busy Growers
• Breeding Techniques
• 7 Gift Ideas for Cannabis Growers
• Grow Journals
• How long can I store nutrient water?
• What is High-Frequency Fertigation?
• Where is it legal to grow weed in the USA?
• See EVERYTHING on the Site!

Safety & Preparation

• Fire Protection in the Grow Room
• Electrical Safety Tips & Tricks
• Prepare Yourself for Growing Emergencies
• Stealth Growing Indoors: How to NOT get Caught Growing Weed

Just for Fun

• Weird or What? Cannabis Mutations & More!
• Creatures on Cannabis (Cute Photo Gallery)
• 10 Gift Ideas for Cannabis Growers

Submit Pics

• Submit Trophy Pictures of your Plants!
• How to Take Better Plant Pics
• How to Fix Yellow HPS Pics

Want More?

• Complete List of EVERYTHING on GWE  ← Full List (Over 500 articles & growing!)

Thanks for visiting! We hope our website helps you find the growing tutorials you were looking for. We’ve written hundreds of growing marijuana articles and unfortunately we can’t fit them all on this page, so we encourage you to use the search bar on the right side (or top of the page for mobile users) to search for articles you don’t see here.

Happy growing!
Nebula & Sirius

Use this “Navigation” page to find the pot growing topic you’re interested in, or click here to see every single page on the website!

The post Link Guide to Growing Cannabis Tutorials appeared first on Grow Weed Easy.

Table of Contents

What Are the Benefits of Great Air Circulation?

Fans: Everything You Need to Know

• Small or Oscillating Fans
• Exhaust Fans (plus how to calculate CFM and which fans are quiet)

Temperature & Humidity Cheat Sheet

Deep Dive into Airflow & Exhaust Systems (transpiration, CO2 injection, suction, seals, and negative air pressure)

How to Control Smells

How to Set Up a Stealthy Exhaust System

How to Make a Hidden Window Exhaust (Examples)

• Fake AC Unit
• Wicker Blinds
• Homemade Fake Window

Cannabis plants love a nice breeze and fresh air. When growing cannabis indoors, you have the ability to control the air circulation and use your exhaust to create the perfect indoor environment for your garden that mimics the best parts of nature.

A good growing environment copies the best parts of nature. This tutorial will show you how to create happy cannabis plants with the perfect environment

This air circulation and exhaust tutorial teaches you how to recreate an environment that makes cannabis thrive, and as a bonus it’ll prevent some types of bugs and mold. By venting out the hot air from your grow lights and pulling in fresh air, you increase your cannabis plant’s speed of growth and yields. Good ventilation pays for itself.

Here are some important points about great air circulation…

Plants Love It

• Faster Growth, Bigger Yields – Plants in the right environment grow faster and produce more buds
• Temperature & Humidity Control – An exhaust system helps control the temperature and humidity levels in the grow area by venting out hot and humid air, while replacing it with fresh air. Fans within the grow area circulate the air to prevent hot or humid patches.
• Prevent Mold & Pests – Many molds and pests like stagnant air, high humidity, and heat. Fresh, cool air blowing over and under your plants will reduce the chance they attack your plants.
• Stronger Stems – A breezy environment strengthens stems so they’re less likely to droop and fall when buds get heavy.

During my first indoor cannabis grow, I didn’t pay much attention to air circulation or creating an exhaust. I had a fan blowing directly on my plants and thought I was good to go.

I found out that growing weed plants without any way to exhaust heat caused the grow area to become too hot and humid, even with small grow lights. This led to several issues, including root problems, white powdery mildew, and heat burn. It could have been much worse because these same conditions can also lead to bud rot, fungus gnats, spider mites, and other unpleasant guests in the grow room.

This grow tent was too hot for optimal growth. I added a cheap ducting fan to vent hot air out and the temperature came down several degrees. A huge improvement.

But there was still a major hot spot directly under the grow light. I added a lot of small fans in this grow space, which helped.

But as soon as I upgraded to a stronger exhaust fan, the inside of the tent turned into a wind tunnel (in fact I had to turn the fan down). I was able to get rid of the small fans and plants still got more than enough fresh air. Bonus: Connect a strong exhaust fan to a carbon filter and completely erase smells before the air gets vented out. With this setup, you can’t smell the plants even in the same room.

Once I started exhausting out air from my grow area, cannabis plants grew faster, and certain problems like persistent droopiness and inexplicable nutrient deficiencies disappeared. It made me realize how many indoor cannabis growers may be unintentionally hurting their plants and yields by missing a few key points about air circulation and creating an exhaust to vent out heat.

Tips for the Best Environment

• Blow Hot Air Out – When it comes to cooling, typically it’s far more effective to blow hot air out of the tent than to try to blow cool air in. Just like how a computer fan is always pointed out.
• Exhaust Fan is Most Important – Small fans in the grow area move air around, but can’t reduce the overall temperature or humidity. On the other hand, a good exhaust fan not only keeps the air moving, but vents hot air out and draws fresh air in. That means if you can only afford one type of fan, it’s better to get a good exhaust fan. Venting and air movement are both important, and a good exhaust fan can do both.
• Use Powerful Fans with Big Plants or Hot Grow Lights – Each leaf is constantly adding water vapor to the air and raising the humidity. If your grow space is full of plants, you need a strong breeze to move the humid air. Along the same line, the more heat produced by your grow lights, the more powerful the fans need to be to move all the heat.
• Erase Smells with a Carbon Filter – If you connect your exhaust fan to a carbon filter, the smells get filtered out of the air before they leave the grow space. This is the most common setup to keep your cannabis plants from stinking up the place.
• Exhaust Systems Can Be Cheap & Stealthy – There are cheap and stealthy ways to create a great ventilation system without a lot of time, money, or effort. You have more options than drilling holes or ducting, and many window exhaust options are undetectable from the outside. Learn how to make a stealthy exhaust!

A grow tent is an inexpensive sealed grow space with built-in holes to vent heat. With a strong exhaust fan pointing out, you don’t need any other fans to get excellent air circulation. This gives you more room in the grow space for your plants.

Looking for a quiet exhaust fan?

If noise is a concern, the AC Infinity Cloudline series fans are a great choice. They’re essentially silent on lower settings, and still pretty quiet at full power compared to traditional exhaust fans.

Make sure to get the right size. AC Infinity fans are quiet but also less powerful than regular exhaust fans like the CanMax. If in doubt, size up.

The AC Infinity Cloudline Series is the quietest exhaust fans we’ve used. In my experience…

• the 4″ version can handle up to a 2’x2’x5′ grow tent and 200W of light*
• the 6″ version can handle up to a 2’x4’x6′ grow tent and 400W of light*
• the 8″ version can handle up to a 4’x4’x7′ grow tent and 600W of light*

*when I used smaller sizes for these setups, the fans couldn’t keep tents cool enough when attached to a carbon filter.

Air Circulation

Air circulation (the way air moves around in your grow space) is an important ingredient in creating a perfect growing environment for your cannabis. Indoor growers strive to create a better-than-nature environment for their plants. The way that air moves has a surprisingly big effect on how your plants will grow.

In nature, cannabis plants thrive in a gentle breeze

Why is Air Circulation Important?

Indoor cannabis plants are normally grown in a relatively sealed environment such as a closet, tent, or room dedicated to growing. The lack of wind indoors can cause some problems compared to growing outside. Outside, in ideal conditions, there’s a breeze flowing through plants, giving them fresh air and strengthening stems. Photosynthesis requires CO2, and a steady supply of fresh air helps cannabis grow faster. Air movement protects plants from certain pests and molds.

Benefits of good air circulation and an exhaust system include…

• Protection against mold, bud rot, and white powdery mildew

• Some protection from pests like fungus gnats and spider mites

• Stems get stronger due to bending & swaying (like in nature)

• Better heat & humidity control for faster growth and bigger yields

Reduce Chance of Mold, Bud Rot & White Powdery Mildew

As air blows over the leaves, it carries away moisture released during transpiration. This allows your plants to drink more water (and pull in more nutrients) at the roots. This regular removal of moisture on the leaves also greatly lowers your chance of running into mold, bud rot, or white powdery mildew.

Protects Cannabis Against Spider Mites & Fungus Gnats

Air flowing over the plants and soil fights against nasty garden pests like spider mites and fungus gnats by making it hard to fly and drying out the top layer of soil.

Spider mites and fungus gnats both love stagnant air and have trouble living in a strong breeze. A breeze also creates a lot of air circulation over the plant containers, which keeps the top layer of soil relatively dry. Dry topsoil makes it hard for pests like fungus gnats to breed (moist topsoil creates a perfect breeding ground for molds & fungus gnats).

Whether growing inside or outside, growers with a nice breeze blowing over their plants and soil tend to get less pests.

Temperature & Humidity Control

Great air circulation combined with an exhaust system helps disperse water vapor and heat evenly throughout the grow space. Small oscillating fans blowing above and below the plant canopy helps equalize the air so there are no hot or humid spots.

An exhaust system ensures that all the air in the grow space is replaced regularly, so plants stay cool, get a fresh supply of CO2, and live in the right humidity. It’s important for plants to be exposed to fresh, moving air for the best growth rates. Learn more about temperature and humidity.

Strengthens Stems

A nice breeze strengthens stems by allowing them to bend and sway like in nature. This builds up the strength of stems over time, which comes in handy when plants start to get big and heavy from buds.

Placing Fans In The Grow Area

Many indoor cannabis growers use small fans to blow air around within the grow area. This creates a nice, breezy environment that cannabis plants love. If your temperature and humidity is under control with your grow lights on, small fans are all you need.

Placing Fans

• Ideally, you’d like a nice breeze surrounding the main canopy, which means you want air blowing above and under the plants.

• Don’t point a strong fan directly at plants because too much wind can damage the leaves and stems. Sometimes you get the best air movement by pointing fans directly at the wall. This disperses the breeze so it’s not too strong.

• After placing fans, gaze around the grow area to make sure that all parts are getting a slight breeze. If you feel stagnant air or a lack or breeze, you may want to adjust your fans.

• Small oscillating fans provide a breeze to a relatively wide area without blowing on any one part too long.

Be Careful! Too Much Wind Causes Clawed Leaves

When there’s too much breeze, the affected leaves will start getting “wind-burned.”

Wind-burned leaves are often curved under and form “claws.” They can look like they’re droopy from overwatering, underwatering, or possibly a nitrogen toxicity, but you know you’ve got wind-burn when the leaves in front of the fan are making claws while leaves further away from the fan look fine.

Just for reference, here’s what too much wind/fan looks like!

Too Much Fan!

Choosing the Right Exhaust Fan & Exhaust System Tutorial

Even when you’re not worried about heat, it’s still important to regularly replace all the air in the grow area, which means you need a way to vent out old air. An exhaust system uses fans and often ducting to move hot and humid air out of the grow space.

Designing an efficient exhaust system will be much simpler if you take the time to understand airflow in a room – the whole idea of setting up an exhaust system is to create negative airflow in the grow space or grow tent so that any hot air is regularly replaced with new, fresh cool air.

All the air in the tent should be replaced by new air every 1-3 minutes for the best results. I recommend aiming to replace the air every one minute unless you live in a cool place. You can calculate the strength of the exhaust fan you need based on the dimensions of your grow space.

In order to move air out of the tent and vent it outside, you need to use at least one strong fan as part of your exhaust system.

How to Calculate Exhaust Fan Strength

In the US, most exhaust fans have a “CFM” rating. This means “cubic feet per minute” and is talking about how much air the fan can move each minute. It’s important to get a fan with the correct CFM rating for your size space.

In addition to CFM, there are 3 sizes that exhaust fans come in as far as diameter (how wide the fan is). They usually come in 4”, 6” or 8”. Generally it’s recommended to get a 6” for most setups since most air-cooled hoods and ducting have a 6” opening. You can also use converters if you need to convert a 6” hold to a 4” fan. 8” fans are usually used for more high-powered grows.

Here’s a short equation to help you roughly determine what CFM rating you need for your fan in your space.

How to calculate CFM needed

1. Determine the cubic area of your space by multiplying Length x Width x Height. You want to exhaust this amount of air at least once a minute.

2. Exhaust Efficiency –  Every exhaust system has some level of inefficiency, which will lower the amount of air being moved by the fan. This step tells you how much extra air-moving power is needed to compensate. In an efficient exhaust system, air goes in a short, straight line after passing through the fan. An inefficient path is when air has to go a long way after leaving the fan, or if the air has to go around turns instead of being in a straight line, or if it has to go through a carbon filter. This step will help make sure your fan is moving enough air to properly ventilate your space.
   • Efficient path / No Carbon Filter- multiply previous number by 3
   • Inefficient path / Carbon Filter- multiply previous number by 5

3. Pick your fan. Inline exhaust fans are measured by CFM (cubic feet/minute), so you need a fan that has a CFM higher than the number you figured out in the last step. However, not all CFMs are equal. If something is listed as a “Booster” fan, it typically is no nearly as strong as an inline exhaust fan with a similar CFM.

Fan CFM Rating Table
(here are some examples of possible setups using the equation above to figure out CFM)

* Of course fans don’t come in these sizes, so round to the closest fan size available.

You’ll generally need a higher CFM rating if your grow space tends to get hot or humid, and it’s usually better to get an exhaust fan that is too big than one that is too little since you can turn it down if necessary.

For example, I used the following exhaust fan in my 2’x4’x5′ tent with a 250W HPS. It’s stronger than I needed by far, and I usually have it set to Speed 1 or 2, but it’s better to have too much airflow than not enough. There have definitely been times, such as during heat waves, where I’ve turned it up all the way to control the temperature.

Some fans are very strong, like this Can Max 6-inch inline fan with 334 CFM. This is the fan I use and I’m very pleased with it even in smaller tents like the 2’x4’x5′. If you get an extra strong fan with a variable speed controller, it means that you can turn the power of the fan up or down at will. This can come in handy if you have a heat wave. For an extra investment, you get a lot more power. This fan has a 201 CFM “low” setting, which uses about ~60W watts, a “medium” 264 CFM setting, and a “high” 334 CFM setting which uses about 75W of electricity.

Avoid “Booster” fans like the one below. I’ve used them before because they are just so cheap (often only around $25 brand new), and the truth is they are better than nothing. BUT, they use a surprising amount of electricity considering how little airflow you get, and you can’t really trust the strength of their CFM ratings. The following 6″ Booster fan uses 37W of electricity for “240 CFM” and yet the airflow is extremely weak compared to the Can Max fan above on its “201 CFM” low setting.

When do you need a booster fan? Most indoor growers with hobbyist-size setups won’t ever need to do this, but if the exhausted air has to travel a long way after going through your fan before it’s vented outside (for example the air has to go through several feet of curved ducting after passing through the fan), a single exhaust fan might not be enough. You may need booster fans along the way to keep the air moving especially around long stretches or tight turns.

Bigger Grow Lights Need Bigger Fans

HPS grow lights are known for producing a lot of heat. This 600W HPS grow light needed a powerful exhaust fan but I was able to keep it cool and breezy with a Can Max 6-inch 334 CFM inline fan.

I quickly need to dispel the common myth that LEDs don’t produce any heat. Although LEDs are known to run cool, even ultra-efficient LEDs produce significant heat at higher wattages. The electricity use of a grow light hints at the amount of heat it will produce. If one grow light draws 300W from the wall, it will generally produce significantly more heat than a grow light that pulls 200W from the wall, regardless of the type of grow light. In other words, power draw from the wall is a rough indicator of the heat to expect from a grow light whether it’s CFLs, LEDs, HPS, or CMH/LECs.

These plants grew under 600W of LEDs (the same electricity as the 600W HPS above) and grown in the same grow tent. Although they produce less heat than the HPS, they still make the tent hot enough that I used the same size exhaust fan. The heat reduction wasn’t enough to allow me to go down a fan size.

If you’re concerned about heat, pay attention to the real power draw when shopping for grow lights.

NOTE: When using a powerful exhaust fan, hang the fan from the top bars inside of your tent to help keep it quiet. If you set a fan on top of your grow tent it will make it sound a lot louder. Learn more about setting up a grow tent for cannabis.

Hang your exhaust fan from inside the tent to help reduce noise

The AC Infinity Cloudline Series are the quietest exhaust fans we’ve used so far.

In my experience…

• the 4″ version can handle up to a 2’x2’x5′ grow tent and 200W of light*
• the 6″ version can handle up to a 2’x4’x6′ grow tent and 400W of light*
• the 8″ version can handle up to a 4’x4’x7′ grow tent and 600W of light*

*when I used smaller sizes for these setups, the fans couldn’t keep tents cool enough when attached to a carbon filter.

When in doubt, it’s usually better to get a bigger exhaust fan than you need, as long as you can adjust the fan speed. You can always turn down the fan if it’s moving too much air. You could also use a speed controller or put the fan on a timer if the exhaust fan is moving air out of your space too fast. There are often times during a grow where it’s helpful to be able to move more air, so size up if you can when it comes to exhaust fans.

In addition to the exhaust fans above, these are two more examples of suitable choices for exhaust fans. These are loud but very effective:

• 4-Inch Exhaust Fan – 195 CFM <– You need a separate speed controller to change the speed of this fan since one is not already built-in.
• 6-Inch Exhaust Fan – 440 CFM <– Not as high quality as my trusty Can Max 6-inch 334 CFM fan listed above (which I prefer), but it’s quite a bit cheaper

This 4-inch exhaust fan is good for small tents with up to ~200W grow light (true power draw)

This 6-inch exhaust fan is good for 4’x4’x7′ tents with up to ~600W grow light (true power draw)

A cheap ducting fan may have a high CFM rating (this 6″ duct fan says it moves 240 CFM) but they don’t have enough power to move a lot of air. If a fan looks like this, it’s going to be much weaker than you’d think from the CFM rating.

Don’t get this type of exhaust fan if you can afford something better!

Passive Intake

A passive intake means that you have a hole for cool air to get in, but aren’t using an intake fan to help bring in extra fresh air.

With every passive intake, make sure your intake holes are in total 3-4 times bigger than your exhaust hole to achieve proper suction and prevent your fan from working too hard blowing out air it can’t replace. You can also help bring air in by having more than one passive intake hole. In other words, the holes/spaces for new air to come in (vents, intake fans, doors, windows) should be bigger than the hole/space where the air is being pulled out of the tent by your exhaust fan.

Active Intake

An active intake simply means that you’re using an extra fan to intake more air. So in addition to your exhaust fan, you also have a fan at your intake hole blowing air in. With an active intake, it’s not as important to have a huge intake hole, since the intake fan will help replace the air. An active intake is often a good idea if your intake hole is the same size as your exhaust hole, or if your exhaust fan is struggling to move all the air.

Keep your grow tent closed if using an exhaust fan. Opening the tent reduces suction and actually prevents the fan from being able to pull the hot air out.

Easy “Exhaust System” Example (No Ducting)

A lot of people want to grow a lot of cannabis but are not willing to install ducting or make a real exhaust system. I understand why – most exhaust systems do not look “stealthy.” Ducting looks incredibly out of place in the home environment. But here’s how to control heat for relatively smaller grows.

Main Idea: Vent hot air directly into the room, then use a window fan to blow it outside

What You Need

• Relatively small grow light (under 300W)

• Access to a window (for example a grow tent in a bedroom)

• Exhaust fan – An exhaust fan that matches your grow light and grow space (examples above)

• Window Fan – I use the Bionaire BW2300 Twin Window Fan because it moves a lot of air and actually fits my huge windows. Another option is the Holmes Dual 8″ Blade Twin Window Fan. Any strong fan that fits your window will work.

A small grow tent provides a great growing environment for smaller grow lights but doesn’t look too suspicious. A few people have seen this grow tent and didn’t mention it.

Here’s what you do (it’s easy)

1. Set up your grow tent with grow light inside

2. Install your exhaust fan at the top of your tent, blowing air out. Make sure there’s an intake hole for new air to get in. The intake hole should ideally be bigger than your exhaust, and should be located on the bottom of the tent on the opposite side of your exhaust fan. This isn’t always possible, but ensures the best results. Most grow tents already have a suitable intake hole, so this is another reason I like grow tents – less work needed on your part to make a good environment for your plants

3. Install window fan blowing air out in the same room as the tent. This window fan will only be effective if the room has an intake hole, just like your grow space. For example, you could open the door to a cooler room or hallway. If it’s cool outside you could open another window in the same room, though be aware if bugs can get in. Basically, there just needs to be a source of cool fresh air to get sucked in when the window fan blows hot air out. In some cases with certain window and room setups, for example if you don’t have a good source of cool fresh air indoors, you might find it more effective to have the window fan pointing in. Experiment if you’re having trouble. Sometimes small changes make a big difference.

This may not be a permanent solution, but it gets the air moving through the tent and keeps the air moving out of the house. You’re basically building an exhaust system without the ducting. It’s not as efficient as using ducting, but for a lot of growers with just a few plants, it’s all that’s needed to control temps in the grow room and tent. As long as it’s cooler outside than inside, the window fan will cool down the room.

This window fan is a “Bionaire BW2300 Twin Window Fan” but any strong window fan will work. They’re available in hardware stores, Best Buy, Walmart, and on Amazon.com. They have extenders so they’ll fit any window snugly, without gaps on either side.

What about smells? All the normal techniques used to control smells will work for this system. The best option to control odors is to create an exhaust system that gives your tent good suction/negative air pressure. Then have your air pass through a good carbon filter just before going through the fan and leaving the tent. With a good strong exhaust system and a quality carbon filter, this will prevent smells in the bedroom or outside except when you actually open the tent. Learn more about carbon filters and controlling smells

Now for growers with bigger grow lights, such as 400W and greater, usually a more robust exhaust system is needed to keep lights cool if the grow space isn’t naturally cool.

Temperature & Humidity Control Cheat Sheet

1.) What is the temperature and humidity where the plants are? If the plants are experiencing temperatures above 85°F (30°C) or humidity above 60%…

• You need to vent air out of the grow space and replace with fresh cool air (full tutorial below)
• Remember that the inside of the space near the grow light is always going to be a few degrees warmer than the room. No amount of fans can make the grow space cooler than the temperature of the room itself
• That means if the room itself is getting warm, you need to find a way to cool the room before you can achieve a cooler grow space

2.) What is the overall temperature and humidity of the grow room? If the grow room feels hot or humid, you can either…

• Vent air out and replace with cool fresh air (for example venting out a window), or
• Use equipment that will actually change the overall temperature/humidity
  • Air Conditioner (AC) – Lowers Temperature, Lowers Humidity
  • Swamp cooler (Evaporative Cooler) – Lowers Temperature, Raises Humidity
  • Dehumidifier or Heater – Raises Temperature, Lowers humidity
  • Humidifier – Raises Temperature, Raises Humidity

Transpiration – Leaves Adds Humidity to the Air

When it comes to air circulation and exhaust, humidity is something you need to pay attention to in addition to temperature.

Leaves are constantly giving off water vapor into the air; in fact, that’s how the plants bring up water from the ground. As the water transpires through the leaves, it pulls up more water from the roots like a straw.

This is known as “transpiration.” Transpiration is a process where leaves give off water vapor. That means that the humidity will always be rising in your grow area unless you find a way to vent that humid air out (or use a dehumidifier to remove the extra moisture).

Transpiration happens via the stomata, little pores that are located on the leaves of the plant. Stomata let oxygen and carbon dioxide in for photosynthesis, while letting water vapor out. A closeup of a single stoma from a tomato plant is pictured to the right.

Plants will open and close the stomata based on the environment. Stomata generally are open during the day and are much smaller at night (when there’s no photosynthesis happening and no need for CO2). Stomata get smaller when the air or roots get dry, which helps the plant stop losing water. By maintaining the proper humidity, your plants grow faster and healthier.

Stomata get bigger when there’s bright light and high humidity since leaves need air for photosynthesis and the plant isn’t “worried” about losing too much water vapor in humid conditions. Because stomata must be open as part of the photosynthesis process, it also means that photosynthesis stops when the plant gets too dry.

Stomata must be open for transpiration to happen, so when the stomata are closed the plant has a hard time taking up water and nutrients through the roots. When there’s too much water in the plant, sometimes the stomata can’t let enough water vapor out, which is part of what causes the symptoms of being overwatered.

Plant leaves can’t get access to CO2 and constantly lose water when the stomata are open, so the plant can’t take in CO2 without also letting water vapor out.

So what you need to remember is that leaves are constantly adding humidity to the air. It’s important to remove this humidity from the grow area if the humidity climbs too high, or it can set up conditions that cause mold, bud rot and powdery mildew.

• To Lower Humidity – Vent out humid air via an exhaust system – the humidity will drop (as long as the new air is less humid)

• To Raise Humidity – Plants can usually adjust to low humidity but if it’s really dry you can turn down the exhaust fan to help raise humidity. Typically, once plants get bigger they’ll be giving off enough water vapor that you don’t need to worry about too-low humidity.

• Large plants raise humidity fast – Small plants don’t put off a lot of water vapor, but larger plants have a lot of leaves releasing water vapor into the air, causing the humidity to rise quickly unless the humid air is being vented out. Remember that most of the water you’re giving to your plants is being released into the air of your grow space, so you need to find a way to get that humidity out, especially in the flowering stage when high humidity can lead to bud rot.

• Dehumidifiers and humidifiers can help control the humidity when an exhaust system isn’t enough

Aim to keep humidity at these levels…

How to control humidity in the grow room: https://www.growweedeasy.com/humidity

CO2 Injection Requires a Sealed Grow Space

In order to use CO2, it’s important to completely seal up the grow room. CO2 is only effective at very high amounts, and you need a sealed grow space to get the concentrations up high enough to benefit plants.

More importantly, CO2 is dangerous to humans at the levels that are recommended for plants. Sealing the grow area is incredibly important to prevent CO2 from leaking into the home.

Learn more about how to use CO2 here: https://www.growweedeasy.com/co2

Suction, Seals & Negative Air Pressure

As far as seals, it’s important that you seal the entire exhaust system after air passes through the exhaust fan. This helps keep the exhaust system efficient. If you’re using a carbon filter, this also makes sure that all air passes over your filter before being vented out of the grow space. A sealed exhaust system along with a carbon filter will prevent smells from escaping outside.

Negative air pressure is something you can create to keep smells from escaping the grow room, so you don’t have smells leaking into the rest of your home..

In order to create negative air pressure, you seal the grow space except for the intake and exhaust holes, which creates suction when you turn on the exhaust fan.

In other words, suction is what you create with seals and negative air pressure.

When your grow tent is bending in from the exhaust fan, it means you’ve got good suction going in there and have created negative airflow. You can also check by burning incense near the intake hole; if the smoke is moving straight to the intake hole you know that you’ve got good negative air pressure bringing fresh air inside.

When you’re in an open grow space without suction like a room or closet, there are not as many universal principles. You may have to experiment with a few different exhaust system setups until you find the best way to manage heat.

Controlling Smells With Your Exhaust

The best way to control smells in the grow room is to use a carbon filter. It is the only method of controlling smells that I recommend for everyone, because it is the most effective and can actually completely scrub smells from the air so they never escape the grow area, either inside or outside the home.

But when using a carbon filter, the way you set up your exhaust is important. Most importantly, the air from the grow area should pass through the filter and be brought straight outside. It needs to completely air-tight after air passes over the filter.

You can set things up a few different ways:

• Carbon Filter (inside) > Air-Cooled Grow Light > Exhaust Fan
• Carbon Filter (inside) > Exhaust Fan 
• Exhaust Fan (inside tent) > Carbon Filter (outside tent)

Important: The Carbon filter needs to be either at the beginning or the end of the line to be effective at reducing smells.  Here are examples of effective carbon filter setups.

Example of carbon filter with air-cooled hood (old fashioned). Note: This worked but the system would be much more efficient with shorter ducting (the longer the air has to travel, the less efficient the system)

Air-cooled hoods are much less common these days. In that case, connect the carbon filter directly to the fan.

Here are some examples:

Carbon filter inside, Fan outside

Carbon filter inside behind light, fan in port

Same setup from a different view. This allows you to move even a big hood almost to the top of the grow space.

An example with an LED grow light

If you’re using a carbon scrubber, it’s important that all air from the grow room goes through the carbon filter before it gets outside. If there are air leaks at any point in the system, smells will escape and the system won’t efficiently cool. By ensuring an airtight exhaust with good suction in the tent, you’ll prevent smells from making it outside or inside the house.

Learn more about controlling smells in the grow room: https://www.growweedeasy.com/how-to-control-smell-when-growing

How to Create a Stealthy Exhaust System

The carbon filter (to scrub smells) isn’t needed in all setups, but the principle for all exhaust systems is the same: Intake cool air and vent out hot air.

What you need:

• Grow Tent (or any sealed grow space with a way to hold up lights and carbon filter)
• Rope Ratchets to hang grow light and carbon filter (usually comes with your grow light, but it’s nice to have extras)
• Grow Light – compare cannabis grow lights
• Exhaust Fan – discover which fan is right for your space
• 6″ Ducting with Ducting Clamps (if you plan on using ducting)
• Carbon Filter (if you want to prevent smells from leaking out of your grow tent) – learn about carbon filters
• A way to hide exhaust vent from outside (if needed, explained below)

Step 1: Set up your grow tent

Step 2: Install both fan and carbon filter(if you plan to use one). These items are often tough to install after the grow light, so get these parts in place before you go to the next step

Step 3: Install your grow lights in the tent with rope ratchets. Don’t plug in anything until you’re about to start growing.

Step 4: Inside the grow tent, connect everything with ducting if desired.

Step 5: Outside the grow tent, install ducting to bring air from fan to exit outside. Use ducting to connect the exit port on your fan to wherever you’re going to exhaust hot air. Try to create a short, straight path that’s as air-tight as possible until air is safely outside.

Step 6: Ensure an intake hole is open so new fresh air can enter the tent. Also make sure that there’s a window or door open in the grow room so fresh air can come inside to replace the hot air being vented out.

The following exhaust system ideas take heat from the grow light and vent it directly out a window with ducting

Tip: Make sure there is no extra slack in the ducting if possible. you will need extra ducting to be able to adjust your lights, but use something like binder clips or chip clips to bunch together extra ducting.

Keeping a straight path that air has to go through will help make the whole exhaust system more efficient.

If things are getting too cold in the grow area (for example in winter months), you can exhaust the heat back into the grow room to help warm things up, or you could turn down the overall air being moved by your fan by putting it on a timer or using a fan speed controller. Some growers even exhaust the heat into the house in the winter for free heating.

Building a Stealthy Exhaust

The next big problem is that a lot of people want to be able to exhaust their hot air without anyone being able to tell from the outside.

Here are some ideas for setting up a stealthy exhaust in a window that looks completely normal from the outside while allowing air to pass through easily.

Fake window AC unit – Use window kit to disguise the exhaust from a grow area.

This method takes advantage of the fact that portable air conditioners come with a special window kit that fits into most windows. This looks completely normal from the outside.

A portable AC usually looks something like this. Notice the classy window fitting.

You can buy a replacement window kit and install it in your window. It has a hole to vent air outside, but looks like you just have an AC. While most ducting won’t fit it without extra help, you can use adhesive foam to help the ducting make an air-tight fit with the exit hole.

What You Need

• Window kit for a portable AC
• Adhesive foam, duct tape or hot glue to connect ducting to window kit
• A way to blackout the rest of your window (for example blackout curtains that don’t let light through but look like regular curtains)

Here’s an example of a window kit available on Amazon.com

This is what a fake portable AC vent looks like in your window from the inside

Wicker Blinds to Hide Exhaust

Having trouble finding a cheap & easy way to stealthily exhaust out hot air from your grow tent? I used a combination of the following items to create an awesome exhaust system for about $45 (just add your fan).

This method takes advantage of the fact that wicker blinds do not allow anyone to see in, but they do allow air to pass in and out.

Wicker blinds offer privacy but still allows air to pass through

What You Need.

• wicker blinds that fit your window
• foam about the size of your window (usually cheaper to buy in person at a hardware store like Lowes or Home Depot)
• corrugated plastic sheet about the same size as your window (also known as “Twinwall Plastic Sheet” or “fluted polypropylene sheet” or “plastic cardboard sheet”). This is often cheaper to buy in person since you can only buy packs of them online. This item can be replaced with another sturdy backing material like wood since you are using this to give structure to the foam, but corrugated plastic is simple to work with and can easily be cut with sharp scissors or a box cutter (no special tools needed).
• duct tape
• 6″ ducting (should match the width of your fan, but the most common exhaust fan size is 6″)
• super glue or hot glue (with any glue, it’s a good idea to read the directions even if you’re already familiar as they sometimes have helpful hints and tips for different types of surfaces)
• staple gun

*All these items can be found at a home improvement store, as they are common items for upgrading around the house

First, hang the wicker blinds in your window like normal. Air can escape through these blinds, but you can’t see through them to the other side. They are commonly used in bedrooms and other windows that lead into private areas.

I bought a huge sheet of foam and glued (super glue and hot glue for best results) it to a sheet of corrugated plastic. You can buy both these items for a few bucks at a home improvement store like Home Depot.

Next, use some ducting to trace a round, duct-sized hole on the foam/plastic. Note: Cut out the duct-sized hole in the foam/corrugated plastic near the top of where it will be mounted. Remember, heat rises, so having the air exit near the top of the window is most efficient.

Run the ducting through the hole you cut, and right up to the wicker blinds. The ducting should be butted up against the wicker blinds so that heat escapes directly outside (since it will be able to pass through the blinds easily). Use duct tape to hold the foam/plastic in place, then use more duct tape to hold the ducting in place. At the end, after everything is placed and you’re happy with how everything looks, you will use a staple gun to staple all your duct tape in place, but don’t worry about that yet.

I also used duct tape to secure the foam to the window because it’s cheap, easy to use, and is very durable when combined with staples.

Normally you want to ensure ducting is as straight as possible, but in this case, make sure that the ducting bends a little during its path. The bends act as a “light trap” to prevent light from being visible behind the wicker blinds.

Use a staple gun to reinforce anywhere you use duct tape, including where the ducting goes through the hole you made in the foam.

I like using foam + corrugated plastic because it’s inexpensive and easy to cut the hole for the exhaust. Having the foam/plastic combo in the window increases the suction in the room so more hot air is vented out and blocks light (no light gets in or out). As an added bonus, the foam dramatically reduces the noise of the fan (so you can just barely hear it even when you’re standing right outside the window).

Awesome Homemade Fake Window

Sent in by a reader named Ray. Love this idea!

This grower needed an entry and exit hole in this window, which is why there are two holes cut out. The hole at the top is going to become the exhaust port to vent out hot air. The hole at the bottom will be how new fresh air enters the grow space.

With a small entry hole like this, the grower would need an intake fan to help move air into the grow space. If this were just a passive intake (no intake fan), then the intake hole should be about 4 times the size of the exit hole. This helps prevent the exhaust fan from working too hard, and will cool the area more efficiently.

This next picture shows the side that will become the front (outward-facing) part of the fake window. This setup allows air to pass in and out freely but blocks light from both sides.

After adding some fake curtains, this secret window exhaust is really starting to come together.

Here’s what that window looks like from the inside when it’s been hooked up. The heat exhaust is on top while the intake is on the bottom.

Completely undetectable from the outside. No one would ever give this window a second glance.

From the grower: “I prefer to use mini blinds, but these curtains were all I had at the time.”

Jump to…

Secrets to Stealthy Growing

How to Control Smells

Choosing the Right Grow Light

MH/HPS Grow Light Tutorial

The post Air Circulation & Exhaust Tutorial appeared first on Grow Weed Easy.

Table of Contents

Introduction

Why Temperature Matters to YOU as a Grower

• Problems With Cold Temps
• Problems With Hot Temps
• VPD: Relation Between Temperature and Humidity

Optimal Temperature at Different Life Stages

Choose the Right Grow Lights For Your Space

How to Control Temperature – Step-by-Step

Introduction

Cannabis plants like a temperature similar to humans, or a little warmer – not too dry, not too humid.

For a lot of indoor growers, that is all you need to worry about. If it feels too hot or too cold for you in your grow area, it’s probably too hot or too cold for your cannabis plants as well.

Cannabis plants like about the same temperature as humans!

If your grow room feels warm or cold, humid or dry, that is a sign that you may want to look into changing the temperature or humidity of your grow area.

Generally, cannabis plants prefer temperatures in the 70-85 °F (20-30 °C) range during the day when lights are on. When grow lights are off (their “night”), cannabis plants are happy with slightly cooler temps.

Optimal Temps For Growing Cannabis

Vegetative Stage: Young growing cannabis plants in the vegetative stage like it a little warmer in the 70-85°F (20-30°C) range. More about temps in the vegetative stage.

Flowering Stage: In the flowering stage (when cannabis plants start making buds), it’s best to keep temps slightly cooler, around 65-80°F (18-26°C). This isn’t for the plants themselves as much as to ensure the best bud quality. Slightly cooler temperatures in the second half of the flowering stage helps produce the best bud color, trichome production, density, and smell. To really bring out colors, aim for a 10°F (8°C) difference between day and night. More about temps in the flowering stage.

Proper temperature brings out colors and can increase bud quality

7 Essential Concepts About Temperature Control

1. Venting is your friend – Hot air should vent out of the grow space if heat is a problem. Vent air to the outdoors if you want to prevent the hot air from being recirculated around the grow room.
2. Fans only push air around – It’s a common misconception that fans bring down the temperature, but fans don’t cool the air. They provide a breeze and help level out the temperature within an area. If it’s hot in your grow tent but cool in your room, then a fan will help equalize the temperatures. But if your entire room is too hot overall, then fans won’t bring the temperature down.
3. ACs and Evaporative Coolers bring the temperature down – Besides exhausting your heat outdoors, the only way to bring the temperature down is to use an AC or Evaporative Cooler. Note: An AC will work in any climate, but evaporative coolers need dry air and only work when the humidity is under 30%.
4. Strain makes a difference – Heat and cold bother certain plants more than others. The strain has a significant effect on a plant’s heat or cold resistance. Get a list of heat-resistant strains.
5. Choose the right light schedule – Too hot during the day or too cold at night? Switch your timer’s on/off cycle, so your grow light is on at night and off in the day. Switching the time your grow lights are turned on will help equalize day and night temperatures. It may even reduce your electricity bill as some people get charged less for electricity used at night. Keeping grow lights off during the day will help with heat, while your grow lights being on at night will keep plants warmer when it’s the coldest.
6. Get Extra Help – Here are 3 supplements that help cannabis with heat stress, and here are some tips for growers dealing with the cold.

Why Temperature Matters to YOU As a Grower

Why Is temperature critical when growing cannabis? Can cannabis stand freezing temps? What happens if your grow room gets too hot?

Different afflictions can happen from high or low temps, so let me break that down for you.

Learn more details below…

Too Low (Cold) Temps

Colder temps will tend to slow down growth. Temps lower than 60°F (15°C) tend to upset plant growth, and freezing temperatures will shock or even kill a cannabis plant. Some plants continue growing in the cold without signs of stress, but they often don’t yield as well as they should given the amount of light they receive.

Plants are also more susceptible to certain types of mold when it’s cool, especially if it’s damp, too. Mold sometimes occurs after frost melts and gets water all over your plants.

Colder temps and significant temperature fluctuations contribute to the over-purpling of leaves and can also reduce photosynthesis.

A plant that is grown in relatively cold temps can survive, but it will never grow as fast or as well as a plant living in a good environment. Indoor plants tend to be much more susceptible to cold than outdoor grown plants.

This plant is drooping after experiencing a cold night

Read some tips about growing cannabis in the cold

Too High (Hot) Temps

While cannabis plants don’t usually die from the heat, too hot temps will cause plants to grow much more slowly.

Please note temps above 80°F (26°C) in the flowering stage will slow down bud growth and may cause them to become airy and loose. The heat can also reduce the potency and smell of your buds. Keeping the grow room temperature under control is especially important in the flowering/budding stage!

In the heat, cannabis is also more susceptible to many problems, including spider mites, white powdery mildew (especially if it gets humid, too), root rot, nutrient burn (from increased water transpiration), increased stretching, wilting due to root oxygen deprivation, and reduced “smelliness” of buds (as terpenes can burn away at higher temps).

More About the Upper Limits of Temperature

• With bright grow lights (such as LEDs or 600W HPS and brighter), cannabis plants of all stages can thrive at slightly higher temps up to a max of about 85°F (30°C) even with no CO2 enrichment, as long as there is low relative humidity and plenty of air movement.

• Cannabis plants can thrive at even higher temperatures, up to an ultimate max of about 95°F (35°C), in an environment with low humidity, extremely bright grow lights, and enriched CO2 (above 1500 PPM) – this is not your average grow! Learn more about CO2 here: https://www.growweedeasy.com/co2-marijuana-yields

• However, it’s essential to pay attention to bud development. Just because the plants are okay doesn’t mean buds are going to be the highest quality possible.

What else is affected by the temperature in the grow room?

• Bud Color – The temperature experienced by your plants influences the color of buds and leaves. The temperature either suppresses or brings out blues, purples, and pinks if your strain has the genetics for it. Learn how to grow pink or purple buds.

• Plant Growth Patterns – Temperature fluctuations can actually change how your plant grows! Warmer night temperatures tend to slow down upward growth. Cannabis generally prefers a cooler temperature at night. Maintaining slightly lower temps during the dark period will encourage your plant to grow as fast as possible.

• Relative Humidity – Temperature has a significant effect on the relative humidity of your grow area.

• Drying & Curing – Temperature is incredibly vital to the drying & curing process. A professional dry/cure is one of the most significant factors when it comes to producing top-shelf buds.

Cool night air can trigger purpling in some plants

Tip: Use Temperature to Help Control Growth!

Cannabis generally prefers slightly cooler temperature at night, and warmer night temperatures will tend to slow down upward growth. But… you can occasionally use this knowledge to your advantage to help control plant growth!

By artificially raising temperatures during the dark period, it will slow stretching plants that are growing too tall too quickly. That means warmer nights can be a helpful way to reduce the “stretch” if you’re growing in a situation where you don’t have a lot of vertical room. And never forget about supercropping, the ultimate way to break down the height of your plant at any time.

By keeping temps a bit cooler during the dark period, you will encourage your plants to grow as fast as possible.

Temperature & Humidity (VPD)

In this section, you will learn a little bit more about how the temperature in your grow room affects the humidity.

Before we talk about VPD, here are some humidity guidelines for growing cannabis

Although those are general guidelines, plants can thrive at different relative humidities depending on the temperature of the air.

Once the air becomes too saturated with water, it tends to form dew or films of water over leaves, which leads to mildew and bud rot. Plants also tend to grow more slowly in very high humidity.

Wet or humid conditions can lead to bud rot

Temperature and relative humidity (RH) are closely related to each other. Sometimes you can overcome a problem with one by fixing the other.

“Humidity” measures how much water is currently “being held” in the air. “Relative humidity” compares that amount to the maximum amount of water that air holds at that temperature.

For example, Warm air can “hold” more evaporated water than cool air

For those interested in learning more about the science behind this, there is a term used by greenhouse growers known as VPD or “Vapour Pressure Deficit,” which roughly measures the temperature and relative humidity.

According to Wikipedia: “the ideal range for VPD in a greenhouse is from 0.45 kPa to 1.25 kPa, ideally sitting at around 0.85 kPa. As a general rule, most plants grow well at VPDs of between 0.8 to 0.95 kPa.”

When growing cannabis plants, relative humidity (RH) is just as important as the temperature of the air and is something you should pay attention to, especially if you notice that your grow room is dry or humid.

If your grow area is particularly dry or humid, you should pay attention to RH (Relative Humidity) in the grow room…

You need to control both temperature and RH at the same time to get the best results when growing cannabis.

• If the air is too hot and dry (high VPD), plants will tend to have slow, stretched growth.

• If the air is too cool and humid (low VPD), plants grow slowly and are prone to problems with mold or fungus.

Note: Pay attention to buds. The best VPD for water moving through the plant does not necessarily match the best temperature/humidity for bud growth, smell, and development. Additionally, each plant is different. As growers, we care more about bud quality than VPD, so make sure to pay attention to your plants before VPD numbers.

Learn more about humidity and growing cannabis: https://www.growweedeasy.com/humidity-growing-cannabis

Clones prefer higher humidity than plants with developed roots

Optimal Temperature At Different Life Stages

Clones

Preference: Comfortable Room Temperature or Slightly Warmer 70-85°F (20-30°C) – High humidity preferred (60-80%)

Clones do not have a root system yet, and so they need to get all their water via transpiration of the leaves until their roots form. Therefore, clones prefer humid conditions with plenty of water evaporated in the air. That’s why many people use a humidity dome or “cloner” to artificially raise the humidity for clones. However, like anything in life, there can be too much of a good thing. You shouldn’t let the humidity get higher than 80% if possible because it can encourage the growth of mold or mildew, and may cause plants to root slower.

Clones seem to root and grow the fastest when the temperature is slightly warm, about 70-85°F (20-30°C), just like a cannabis plant in the vegetative stage.

Learn more about cloning cannabis plants here: https://www.growweedeasy.com/complete-guide-cloning-marijuana

Did you know you can clone cannabis in a cup of water?

Seedling & Vegetative Stage

Preference: Comfortable Room Temperature or Slightly Warmer 70-85°F (20-30°C) – Avoid very low humidity

Young seedlings tend to grow faster with mid-to-high humidity and warm temperatures.

However, a cannabis plant’s ability to withstand drier and colder/warmer conditions tends to increase as it gets older. Outdoor-grown plants tend to be much more robust about temperature fluctuations than indoor plants.

It’s good to aim for a temperature of 70-85°F (20-30°C), during the vegetative stage. It’s not always possible, but try to give plants slightly cooler temps during the dark period than during the light period as long as you stay within the recommended range.

Maintaining slightly cooler night temperatures (in the specified range) tends to promote the fastest and healthiest vegetative growing for cannabis plants.

Two happy vegetative plants getting a comfortable 75°F (24°C)

CO2 Enrichment Changes the Optimal Vegetative Temperature

Vegetative cannabis plants like higher temps when you supplement the grow room with CO2, but there are a few critical things you must know about CO2.

For CO2 enrichment to be successful, you must… 

• Seal the environment and maintain at least 1500 PPM of CO2 in the air
• Provide a lot of light (more light than your plants would typically be able to use)​
• Keep temperatures between 85°F (30°C) and 95°F (35°C).
• Avoid high temperatures after buds start forming, so they develop properly

​Learn more about CO2 here: https://www.growweedeasy.com/co2-marijuana-yields

Flowering Stage

Preference: Avoid hot temps! 65-80°F (18-26°C) – Mid-to-Low humidity – Slightly cooler at night than during the day

In general, you should strive to keep temps under 80°F (26°C) throughout the flowering stage, and especially towards the crucial second half when buds are in the midst of development.

The temperature in the flowering stage is too important to ignore. That’s because keeping temps low during the flowering stage will help your plants produce the most potent, dense, smelly, and trichome-covered buds as possible.

Unfortunately, higher temperatures during the flowering stage can cause plant problems and slowed bud growth. It can also cause terpenes and potency to evaporate into the air.

What that means is if your buds stay too hot during the flowering stage, the higher temperature may accidentally be burning away some of your terpenes and cannabinoids (reducing the final taste/smell/potency of your buds after harvest).

Read more about how to improve the taste and smell of your buds here: https://www.growweedeasy.com/better-taste-better-smell

It is especially important to make sure buds are not exposed to too-hot temps after week 6 or 7 of flowering, as this is when the terpene content in the buds starts to ramp up.

Give plants colder temperatures at night, especially towards the end of the flowering stage

Note: Slightly chilly is okay, but never expose your plants to freezing temps!

Too-cold air can cause buds to grow airy and loose

Bonus! In addition to improving taste and smell, terpenes can affect the color of plants and cannabis buds. For example, terpenoids are what gives tomatoes their red color. The same process may be at work with certain cannabis strains, too. By maintaining lower night temperatures in the last few weeks before your cannabis harvest, you will help bring out colors in your cannabis (purple, pink, blue, etc.). Of course, this only works if your strain has the genes to produce colored cannabis buds. Most strains will only grow green buds, but if your plant can produce other colors, cooler night temps can help bring them out!

Drying & Curing Buds

While starting with good genetics and properly caring for plants is key to growing top-shelf quality buds, your job isn’t over when you cut down your plants at harvest. I’d say that almost 50% of the final bud quality is determined after you cut down your plants, but how you choose to dry & cure your buds.

Buds that have been professionally dried and cured are more potent, denser, smoother to smoke, look better, and have that coveted “sticky-icky” feeling.

The main thing you must do as a grower to professionally dry and cure your buds is to maintain the proper temperature and humidity during the process. If you follow the right method, you never have to worry about mold or overdrying, and you will get beautifully cured buds every time.

Learn more about how to professionally dry & cure your buds here: https://www.growweedeasy.com/how-to-cure-buds

Choose Proper Grow Lights For Your Grow Area

Many cannabis growers worry about how their indoor grow lights will affect the temperature of their grow room. Heat production from grow lights is a valid concern, and this section will break everything down for you.

Get a complete breakdown of ALL cannabis grow lights

Fluorescent Lighting

I generally don’t recommend growing cannabis plants under fluorescent grow lights. In almost every case, you’ll get better results (bigger yields, less heat, higher density) by growing weed with LED grow lights instead.

But for some growers, or in some parts of the world, fluorescent lights are your best choice, in which case they can be used. However, the struggle is you need to keep them very close to your plants, within 4 inches (10 cm) from the tops of buds, to get good results in the flowering stage.

Fluorescent lights are underpowered and good poor yields and bud density unless you keep them extremely close to buds as they form.

Learn about other fluorescent grow lights here

Learn how to grow 3 oz of weed with a small LED for under $300

HID Grow Lights – Metal Halide (MH), High Pressure Sodium (HPS) & LECs/CMH

MH/HPS/LEC grow lights are known for using a lot of electricity and producing a lot of heat. And while that’s true for the bigger models of HID lights, I think a lot of growers overestimate how much heat will be produced by the smaller HID models.

For example, a lot of people recommend that new growers get CFLs instead of HIDs so that there’s less heat in the grow room. Yet it’s essential to keep in mind that 250W of HPS light will produce about the same amount of heat as 250W of CFLs, except that you’ll get more light and better yields with HIDs. Another advantage of HIDs over smaller lights like CFLs is good models of HIDs come pre-built to accommodate cooling via an exhaust system.

That’s why it’s easier to cool an equivalent amount of HIDs compared to CFLs.

However, HIDs do need more height than growing with CFLs, so if the height is limited, than HIDs may not be the right choice for you.

But, if you do have the height to accommodate an MH/HPS light, I highly recommend going for that over CFL grow lights. In my opinion, CFL grow lights a best in very short/tight spaces where ultimate stealth is the biggest goal.

Learn more about MH/HPS grow lights here

Learn About LEC/CMH grow lights (highly recommended as it seems to beat other HID lights for yields, smell, and trichome production)

LED Grow Lights

LEDs are known for needing just a little electricity and for producing less heat than HID grow lights like MH or HPS lights.

But is all the marketing hype true?

It’s actually a lot more complicated than just a “yes” or “no” answer. The truth is, some LED grow lights work incredible, and some are a ripoff. It’s helpful to educate yourself about LED grow lights to make sure you get exactly what you’re looking for.

Learn more about LED grow lights here

How to Control Temperature in the Grow Room Step-By-Step

1. Get a Thermometer
2. Refer to Optimal Temperature Chart
3. Correct High or Low Temps (explained)

Step 1: Get a Way To Monitor Temperature (Thermometer)

In addition to measuring the temperature, it’s also important to know the relative humidity (RH) of your grow room. So you might as well get a thermometer that measures both temperature and humidity at the same time.

But it’s not necessarily that easy. The quest to find the perfect thermometer/humidity monitor can be tough.

While you can find cheap ones at the local store, you may notice that a lot of the cheaper models are a few degrees “off”. A few degrees probably won’t have a massive effect on your results, though. Some growers will buy 2 or 3 different thermometers and use the average to determine what’s really going on in the grow room. I have several that I’ve picked up over the years, and they all sit in my grow room now.

Here’s a popular thermometer/hygrometer that has all standard features and costs $12

This thermometer was made for incubating chicken eggs, which is why the humidity number is displayed so prominently (humidity is critical to egg hatching rates). I’ve found that many thermometers slowly die from the heat of a grow light, but this particular one keeps on trucking despite the extreme environment. I bought one over 5 years ago, and it still works great.

This thermometer ($25) is resistant to heat from grow lights

It can be tough on the quest to find the perfect thermometer/humidity monitor, especially if you don’t want to spend a pretty penny. I like this one. It only costs $8, and it comes with a probe. I have the probe hanging in my grow tent near the plants, with the screen outside the tent. This setup makes it easy to see the temperature and humidity exactly where the plants are without having to open the tent.

I like that this thermometer/hygrometer ($8) has a probe you can hang in the grow space.

Step 2: Refer to Temperature Chart

Chart – optimal temperature for growing cannabis plants

Vegetative Stage: 70-85°F (20-30°C)

Flowering Stage: 65-80°F (18-26°C)

If your temperature is too high or low….

Step 3: Correct Too-High or Too-Low Temps (explained)

There are many tools available to help you control the temperature of your grow room.

Both hot and cold in your grow room? For those who struggle with both hot and cold temps where you live, you may want to consider getting an All-in-One Heater & Air Conditioner.

Too Hot: What to Do

1. Exhaust System: Make sure you have a sound exhaust system to pull out hot air and increase air circulation to your plants. If you don’t have an exhaust fan pulling hot air from your grow lights outside, fixing that is your first step. Remember! An exhaust system is important not only keeps temps down; it improves the air circulation your plants need to thrive. Learn how to set up a proper exhaust system here: https://www.growweedeasy.com/hps-grow-lights-setup

Tips for controlling the heat in the grow space using an exhaust system

2. Air Circulation: If there is a lack of proper air circulation in the grow room,  you will tend to get hot spots that can damage your plants. It’s always a great idea to install fans in the grow room to help circulate the air inside the tent. Remember, don’t point fans directly at plants. Leaves can be rustling slightly, but stems should not be waving around due to the direct breeze of the fan. I like to point fans somewhat over or under the canopy, so it doesn’t aim directly at plants. Sometimes I point the fan at a wall to move the air around without blowing on the plants.

3. Change the Light Schedule: If you’re in a situation where the temperature is climbing too high at specific parts of the day, then you can change your light schedule so that your grow lights are off during the hottest part of the day. For example, in the vegetative stage, your plants need 18+ hours of light each day. If it gets too hot in the middle of the day, you could set your timer to turn your lights off for 6 hours during that part of the day. This strategy will not fix a major heat problem but can help alleviate symptoms of heat stress during a short hot spell or heatwave.

4. Consider Getting Different or Smaller Grow Lights: Learn about different grow setups.

5. AC or Evaporative Cooler: If you have good air exchange and have tried all the steps above, but the temperature in the grow area is still too hot, you will need to use a piece of equipment that can lower the temperature of the air.

6. Get a Heat-Resistant Strain: Some strains can naturally handle heat without a problem.

Air Conditioner – (some are portable, some ACs fit in your window) – in addition to cooling the air, an AC will also tend to lower the relative humidity of the air. To be effective, and AC must be able to exhaust hot air outside the house, just like hot grow lights. If the air outside the grow tent is already too warm, you will need to get an AC to pre-cool the air before it enters the grow tent. No matter how strong your exhaust system, it won’t be able to bring the temperature lower than your ambient room temperature. If you need to lower the ambient room temperature, you’re going to need a way to cool the air, and air conditioners are hands-down the most effective way to cool your air.

Swamp cooler – (also known as an “evaporative cooler”) Ideal for those where it’s both hot & dry as the swamp cooler will bring down temps while also adding additional humidity to the air. Works best when humidity is too low, and the temperature is too high. Repeat: these do NOT work well if your humidity is above 30% RH! Read how one user used a swamp cooler to control his temps & humidity.

Too Cold: What To Do

If it’s too cold in your grow room, sometimes you have additional options besides just getting a heater, such as getting a stronger/hotter grow light or using extra insulation to contain the heat of the grow lights you do have.

If your plant is not insulated from the cold (for example, if it’s growing in the middle of your garage, basement, attic, etc.), then the first step is to make sure your plant is adequately insulated. It’s cheaper and easier to insulate a small space, so create a dedicated grow box or get a grow tent that will act as the outward bounds of your grow area.

Then you can buy rolls of insulating materials for cheap at your local home improvement store and use these to insulate your grow area further. Insulation will help keep the cold air out, and the hot air inside.

Reflectix material is both reflective and insulating. Line the inside of your grow space to help contain heat.

With a properly insulated grow box, your grow lights will likely provide enough heat to keep your cannabis plants warm unless you live in a freezing cold area, or perhaps if you’re in the middle of winter or a cold spell.

If you must get a heater to keep your plants warm, avoid letting it blow hot air directly on your plants, and especially avoid ever having it in the tent with your plants. You want a heater that radiates heat out evenly, instead of pushing out a blast of hot air like a space heater. Never allow hot air to blow directly on any part of the plant. Most heaters can turn on and off depending on the temperature, so they turn off when unneeded.

The following model of heater is an excellent example of the type of heater you want for your grow room – it puts out gentle heat and has a thermostat you can use to have it automatically turn on and off as needed. The heat radiates out instead of being pushed out (which you don’t want in your grow room). It’s almost entirely silent. Plus, it comes with a timer, so you can have it preset to turn on just before lights go off for the night (or whatever you need for your space).

This heater gently radiates heat instead of blow hot air

Keep roots warm and up off the cold floor

If you’re growing in a basement or garage, it’s common for the floor to be cold. If growing plants in containers, it can help to put them on a piece or some other barrier to prevent them from sitting directly on the floor.

Some people are growing in a garage or attic that is okay during the day but is getting too cold at night when their grow lights go off.

It can help to switch your timer’s on/off cycle, so your grow light is on at night and off in the day.

Switching the light schedules helps equalize day and night temperatures. Keeping grow lights on at night will keep plants warmer when it’s the coldest.

Change your timer so grow lights are on at night

However, to get most cannabis plants to start making buds, you need to give them at least 12 hours of complete darkness every night, which means grow lights need to be off for 12 hours/day. For some growers in a wintry climate, a 12-hour dark period (even during the day) will send the temperature plummeting too low.

But did you know there’s a type of cannabis that will make buds even if you leave your grow lights on for 24 hours a day?

​​​​Auto-flowering strains let you keep your grow lights on for 24 hours/day, which helps keep plants warm in cool growing areas!

They are described as “auto-flowering” because these strains will automatically start making buds and be ready to harvest in about 3 months, no matter what light schedule they get! This lets you leave your grow lights on all day, every day, so your plants stay warm!

Learn more about auto-flowering strains!

An example of autoflowering plants

Be Prepared For When the Electricity Goes Out!

One challenge for growers in wintry climates is the impending chance of a power outage during the winter months. Indoor growers rely on electricity to keep plants alive, especially in the winter, so try to prepare ahead of time!

Learn How to Prepare for a Power Outage!

And while you’re here…

Learn How to Prepare for Other Common Growing Emergencies!

Strain Makes a Difference!

Some strains are much hardier than others when it comes to the cold. If possible, it helps to pick a cold-resistant strain. Learn where you can get seeds.

One advantage of cold temperatures is it tends to bring out colors like purple and pink

Jump to…

Complete Guide to Cannabis Grow Lights

10-Step Quick Start Grow Guide

7 Steps to Growing Top-Shelf Buds

Advanced Growth Techniques

The post Cannabis Temperature Tutorial appeared first on Grow Weed Easy.

Table of Contents

• Introduction
• Why Humidity Matters to YOU
• Effects of Poor Humidity Management
• Humidity Basics
  • Clones
  • Seedling & Vegetative Stage
  • Flowering Stage
  • Drying Buds
• Temperature & Humidity (VPD)
  • Too Cold?
  • Too Hot?
• How to Control Humidity in the Grow Room
  • Step 1: Get a Humidity & Temperature Monitor
  • Step 2: Refer to Humidity Chart 
  • Step 3: Correct Levels That Are Too High or Too Low (explained)
• One Grower’s Story – Dealing with Low Humidity in Denver

Introduction

If you want to grow sticky, high-potency buds, your cannabis will demand attention to its many needs.

One need of the growing cannabis plant – that is commonly overlooked – is humidity.

Believe it or not, humidity is actually very important to your plant! Humidity will help determine your plants resilience against mold/mildew in addition to how much your plants need to drink. Getting it just right can improve plant growth and increase your yields.

Luckily, there isn’t much to learn, so you can be the master of humidity in your grow with very little effort! Today we will give you the information you need to have complete mastery over humidity and thus, give your plants a boost in production.

Why Humidity Matters To YOU

In all stages of cannabis growth your plants will have a constant need to intake water, and the amount of water they need fluctuates with the humidity in your grow room. When the humidity is high, cannabis plants use their leaves to absorb moisture from the air which causes them to drink less water from their roots. Conversely, when the humidity is low, they will pull more water in through their roots.

Since humidity changes how much water your plants drink, and the water you give your plants have nutrients in them, being in control of humidity gives you increased control over your plant’s nutrient intake.

But controlling humidity isn’t just about prevention…having the right humidity encourages strong, healthy, leafy plants with vigorous growth. In fact, growing with DWC (Deep Water Culture) / Bubbleponics during vegetation with the correct humidity can actually turn into a struggle to tame out-of-control plant growth!

Additionally, after your plants start making buds in the flowering stage and get close to harvest, you can manipulate the humidity of your grow area to get your plants to produce more resin (trichomes/glitter which contain THC and other cannabinoids) while preventing plants from being attacked by mold. High humidity can sometimes cause mold or bud rot – a grower’s worst nightmare for those fat, dense main colas.

Effects of Poor Humidity Management

We’re not out to scare you, but you should know what happens to a grow room with poor humidity management. We know how important humidity is because we’ve experienced every one of these problems firsthand!

White Powdery Mildew

• White Powdery Mildew is a fungal disease that will shows up high humidity environments. This can be tricky since young cannabis plants flourish in humid environments. Luckily, you can stave off WPM by making sure there is proper airflow in your grow area; a small oscillating fan – even on the low setting – works wonders.

Bud Mold or Rot

• Bud rot or mold is – in my opinion – one of the worst pains a grower can experience as a result of poor humidity management. Imagine harvesting a huge, dense main cola from your plant only to see the insides are totally white or brown with mold. Buds in this condition are unusable and 100% should be thrown away.

• Learn about mold-resistant cannabis strains

Nutrient Problems

• Humidity is a factor that partly determines how much your plants will drink. If the air is dry, your plants will tend to drink more at their roots. If they’re already drinking more due to high temperatures, low humidity can cause them to drink a lot of water through their roots and uptake too-high levels of nutrients. If your plant takes in more nutrients than the plant can use, the leaves will begin to show yellow or burnt tips, which is the result of nutrient burn. Sometimes too-low humidity can cause other apparent nutrient problems.

Slowed Growth

• Cannabis plants love higher humidity when they’re young, and lower humidity when they’re mature. To be frank, if they’re not getting these conditions, they may not be growing nearly as fast or healthy as they could.

Humidity Basics

Okay, so now you know why you need to manage humidity when growing cannabis, but you may not know what humidity you are aiming for. This chart is the quick-and-easy answer:

Humidity is actually a measure of how much water vapor is being “held” in the air. There are different ways to measure humidity, including “absolute,” “specific,” or “relative” humidity.

Most growers are talking about Relative Humidity or RH when they talk about humidity in the grow room.

Relative humidity measures how much water is in their air compared to the maximum amount of water that can be held in the air at that temperature.

Below is a quick reference for the major stages of the cannabis life cycle in regards to the relative humidity you are aiming for. We’ll go through them all in more detail

• Clones
• Seedlings & Vegetative Plants
• Flowering Stage
• Drying

Clones

Optimal Humidity is 70% RH

Clones need time to develop a root system to intake water. Young clones are solely dependent on getting water through their leaves from the air and this is only possible with high humidity.

Maintaining high levels of humidity will dramatically increase the chances of clones rooting successfully, and will increase young clone growth.

This is why many growers use a humidity dome for new clones!

Here’s a step-by-step picture guide to cloning cannabis:
https://www.growweedeasy.com/complete-guide-cloning-marijuana

Young & Vegetative Plants (seedling to end of vegetative stage)

Optimal Humidity is 40-60% RH

Seedlings and young cannabis plants in the vegetative stage grow a lot of leaf mass in a great growing environment, and plants can sometimes grow foliage at a faster pace than the roots.

But the roots aren’t the only way your plant gets water. Leaves can actually pull water vapor directly out of the air, and higher humidity in the air allows the leaves to get more water to the plant if needed. Until your plant has fully developed roots, low levels of humidity in the air can cause growth to be slower.

The ideas is to create a comfortably warm environment that mimics springtime or summer.

Warning Signs:

• Don’t give seedlings a humidity dome unless it’s very dry where you live. They need springtime conditions, but it can be easy to go overboard with seedlings (compared to clones which love high humidity).
• The RH is too high if the plants are forming wet spots on their leaves even when they’re not touching each other
• As seedlings get older and become young plants, they want the humidity around 50% RH
• If the RH drops below 25%, the dry air tends to limit growth and cause nutrient problems to appear on leaves, especially for young seedlings. Some seedlings are fine, but other plants are particularly sensitive to humidity.

Humidity for flowering plants

Optimal Humidity is 40-50% RH

Ideally, the relative humidity of your grow room should be lowered to around 40-50% at the beginning of the flowering stage. As plants approach harvest, some growers lower humidity down below 40% or even less to force cannabis buds to produce more resin, though I’ve seen that can majorly stress some plants, so that technique should be used with caution. Definitely lower the humidity just a little at a time to see how plants react before putting your plants in an extreme environment.

By the beginning of the flowering stage, your cannabis plants have created a large root system to fulfill their water needs. They will still be able to take in water through their leaves, but maintaining a relatively lower humidity than the vegetative stage helps prevent molds or mildews from forming.

Mold is especially dangerous in the flowering stage because it can form on or inside your buds or colas without you knowing. If you find that you have mold growing in any of your buds, or buds are rotting from the inside, you should immediately throw all of the contaminated buds away. Bud rot can ruin entire harvests, so if one bud is infected thoroughly search your grow room for more. If you can’t lower the humidity and already have a rampant mold problem, the best choice might be to cut your losses and harvest immediately to avoid any other buds getting bud rot.

Even if the humidity is low, it is still important to have air moving over and around your plants. Small fans blowing over and under the plant canopy will help keep air moving so that wet spots don’t form around any parts of the plant.

Extra resin production

• During the last 2-3 weeks before harvest, some growers will use a dehumidifier to drop the humidity of their grow area to between 40-45%. This not only prevents bud rot during the last few weeks, the lower humidity may stress the plant in just the right way to increase resin production. As a result, you harvest extra-potent buds with more sparkly trichomes. While this technique has not yet been proven to increase resin, many growers swear by it. Just be aware that lowering the humidity too much can cause stress to some plants (other strains react well).

Humidity for drying buds (early stage cure)

Optimal Humidity in the Drying Room is 55% RH (for beginners)

Keeping the humidity around the 50% range will allow your buds to dry, but keep them from drying too quickly.

This range is also optimal for preventing mold, so it doesn’t get any better for drying if you’re a beginner!

As an advanced drying and curing technique, some growers like to keep the humidity a little higher so buds dry slower (which could possibly increase the quality of your cured buds). Drying with high humidity is considered an advanced technique because drying must be done with extra care to prevent mold forming on your harvested buds!

It’s good to have air circulation in the drying area, but it’s recommended that no air is being blown directly over the buds to prevent them from drying too quickly. More information in the link below!

Learn how to dry and cure buds for professional results every time (no more guesswork!): https://www.growweedeasy.com/how-to-cure-buds

Temperature and How It Relates to Humidity

Temperature and relative humidity are closely related to each other.

Relative humidity is measuring how much water is “being held” in the air compared to the maximum amount of water that can be held at that temperature.

Warm air can “hold onto” more water than cool air. Plants will tend to thrive at different relative humidities depending on the temperature of the air. Once the air becomes too saturated with water, it will tend to form dew or films of water over leaves, which leads to mold.

Temperature and humidity affect each other. For example, warm air “holds” more water.

For those interested in learning more about the science behind this, there is a term used by greenhouse growers known at VPD, or Vapour Pressure Deficit, that roughly measures the temperature and relative humidity.

According to Wikipedia: “the ideal range for VPD in a greenhouse is from 0.45 kPa to 1.25 kPa, ideally sitting at around 0.85 kPa. As a general rule, most plants grow well at VPDs of between 0.8 to 0.95 kPa.”

When growing plants, temperature is just as important as the Relative Humidity (RH) of the air, if not even more so! You need to control both temperature and RH at the same time to get the best results when growing cannabis.

• If the air is too hot and dry (high VPD), plants will tend to have stretched growth.
• If the air is too cool and humid (low VPD), plants are more prone to problems with mold or fungus.

Here’s what that means to you, the grower:

Cannabis likes a comfortable room temperature, or a little warmer – not too dry, not too humid. For most growers, that is all you need to worry about.

If your grow room feels warm or cold, humid or dry, that is a sign that you may want to look into changing the temperature and/or humidity of your grow area.

Generally, cannabis plants prefer temperatures in the 70-80 °F (21-27 °C) range during the day when lights are on. When lights are off (or at night), cannabis plants are happy with slightly cooler temps.

What if it gets too cold?

Colder temps will tend to slow down growth. Temps lower than 60°F (15°C) can upset plant growth and freezing temperatures will shock or even kill a cannabis plant.

Can cannabis stand higher temps? What if my grow room is too hot?

Please note that too-high temps in the flowering stage will not only slow down bud growth and cause fluffier buds, but it will also tend to reduce the potency of your buds by causing some terpenes and cannabinoids to burn off. Keeping the grow room temperature under control is important in the flowering stage!

Advanced Tips

• With bright grow lights (such as 600W HPS and larger), cannabis plants can thrive at temps up to 85°F (30°C) even with no CO2 enrichment, as long as there is low relative humidity and plenty of air movement.
• Cannabis plants can thrive at higher temperatures, up to an ultimate max of about 95°F (35°C), in an environment with low humidity, extremely bright grow lights and enriched CO2 (above 1500 PPM) – this is not your average grow!
• Cannabis prefers slightly cooler temperature at night (warmer night temperatures will tend to slow down growth – so you can use this knowledge and raise night temperatures to slow down stretching plants that are growing too tall too quickly)

How to Control Humidity in the Grow Room

Step 1: Get a Humidity & Temperature Monitor to see if you need to adjust anything

The digital ThermoPro TP50 is cheap and accurate. It also lets you know what the highest and lowest readings have been, so you’ll know if you’ve been getting major heat spikes.

But even better, there are some thermometers that let you remotely check the temperature and humidity via your smart phone, and even track how your temperature and humidity are changing over time. This particular model comes with a strap that can make it easier to hang near your cannabis plants, so you’re measuring the air exactly where your plants are.

Govee WiFi Thermometer Hygrometer H5179 lets you monitor the temperature and humidity remotely.

Step 2: Refer to Chart

Ideal temps are 70-80 °F (21-27 °C) during the day (lights on) and 5-10 degrees cooler at night (lights off).

Refer to the following chart to determine if relative humidity is in the ideal relative humidity range:

• Young plants (seedling to end of vegetation)

  • 40-60% RH (if you see wet spots forming on the leaves, humidity is too high or you need to increase air circulation). Beware of white powdery mold in humid grow spaces!

• Flowering plants (making buds)

  • 40-50% RH (a little less humidity helps protect plants from mold – during the last few weeks of flowering, a lower RH can possibly increase resin production as buds approach harvest)

Step 3: Correct humidity and/or temperature that is too high or too low

Many indoor growers tend to deal with too much heat and high temperatures – this is because grow lights can get very hot, and cannabis grows are often confined to very tight spaces due to stealth or privacy concerns.

The relative humidity of your grow area depends mostly on where you live, and how you’ve chosen to construct your grow area. Many growers struggle with lowering their humidity, because the mass of leaves and vegetation in a small grow area tends to cause the humidity to go up.

Here’s how you can correct common cannabis problems with heat and/or humidity.

Humidity:

• Humidity is too high – How to lower Humidity
• Humidity is too low – How to increase humidity

Temperature:

• Too hot – How to lower temperature safely
• Too cold – How to safely warm things up

Humidity is too high – how to lower humidity

• Dehumidifier –  will pull moisture from the air in a small area like a grow room or tent – a good one can be hooked directly to a drain for very humid areas like the UK and other humid parts of the world, otherwise dehumidifiers will automatically shut off when full and you will have to manually remove the water that it collects from the air.

• Increase ventilation (add a more powerful exhaust fan or otherwise improve your exhaust system) – this increases the total amount of airflow in the grow area. This strategy will only work to lower humidity if the intake air has a lower RH than the air in the grow room.

  Advanced: If you do get a high-powered exhaust fan to lower humidity, you may want to consider getting atmospheric controller with a humidity setting to automatically adjust the fan speed to achieve the humidity you want.

• Avoid over-watering plants – soggy soil (or leaving extra water in plant trays sitting in the grow area) will tend to raise the humidity of the grow room

• Consider slight defoliation – very leafy plants will tend to raise the humidity of the grow room, especially when there isn’t good ventilation or air flow.

• Air Conditioner (some are portable, some ACs fit in your window) – tends to lower humidity (in addition to cooling the air)

Humidity is too low – how to increase humidity in dry air

• Humidifier – will add additional moisture to the air, I like the evaporative type of humidifier because it also works to cool down temps slightly. Make sure you get a humidifier with a large holding tank (holds at least 6 gallons of water at a time). Those “one-room” humidifiers with a 1.5 gallon tank often need to be refilled several times a day.

A “swamp cooler” or evaporative cooler will cool down air while increasing the relative humidity; works best when humidity is too low and temperature is too high. Read how one user used a swamp cooler to control his humidity.

This humidifier is an evaporative swamp cooler that holds 7.5 gallons of water at a time – great for hot, dry climates.

Temperature is too high (too hot) – how to lower temperature & cool things down

• Increase ventilation (add a more powerful exhaust fan) – this increases the total amount of airflow in the grow area. This strategy will only work to lower temperature if the intake air has a lower temperature than the air in the grow room (if the air outside is hot, too, adding more ventilation won’t do much to lower the temperature)

• Air Conditioner (some are portable, some ACs fit in your window) – in addition to cooling the air, an AC will also tend to lower the relative humidity of the air

• Light Schedule – Consider having your lights turn on during the cooler parts of the day (for example some growers have their lights on at night, and keep lights off during the hottest parts of the day)

Temperature is too low (too cold) – how to raise temperature & heat things up

• Insulation – Consider insulating your grow box or grow tent with something that holds in the heat. For safety reasons, it’s good to get insulation that is resistant to heat.

• Bigger grow light – Get a bigger grow light to produce more heat within the grow space (and get plants to grow faster!)

• Heating mat – placed under plants

Check It Out!

Monitor temperature & humidity in your grow room!

Govee WiFi Thermometer Hygrometer H5179 lets you monitor the temperature and humidity remotely.

Monitor temperature & humidity even while you’re away!

Too Hot, Too Dry – Humidity Story from a Grower in Denver

by thatsnotmybike

I’m preparing things for my first grow and trying to make sure that I plan everything ‘right’ and I’m not surprised by too many things, and hopefully none too late to fix.

Humidity has me confused. I’ve seen sources saying the greater the humidity the better, some that say humidity makes no difference as long as the plant is hydrated, and some claiming nothing will grow if you’re not nailed at 45%.

The ambient humidity near Denver is pretty low – the room I plan to grow in sits at 20% on average. Is this too low for my plants to be happy?

Answer:

This humidity is too low for healthy growth of cannabis plants. This grower decied to build something known as a swamp cooler:http://burningman.rengeekcentral.com/ swampcooler.html

It moistens the air while keeping the temperature down, which can also be a problem in Denver.

Update from the grower: For anyone stumbling onto this in the future, the swamp cooler in the link above is friggin awesome. I have it connected to my intake ducting and it’s keeping the cabinet at 73F with 80F outside temps! I cannot downplay how great it works, but I recommend creating a way bigger reservoir, so you don’t have to refill it every 6-8 hours.

Jump to…

7-Step Remedy to 99% of Cannabis Growing Problems

Cannabis Symptoms by Picture

Compare Different Grow Lights

Learn about Increasing Yields with CO2

The post Indoor Humidity Control for Cannabis Plants appeared first on Grow Weed Easy.

Quick Summary: Best way to stop weed smell is a carbon filter in a grow tent. Example no-smell cannabis setup with grow light (~10 oz harvest).

What’s that smell?

Have you ever caught a hint of marijuana smell in the breeze?

Even if you couldn’t spot the source, you wouldn’t doubt what your nose told you.

I love that pungent, unique marijuana smell. Unfortunately, this delightful aroma is instantly recognizable and can stir up trouble for a cannabis grower.

Why? A grow room with flowering marijuana plants is a factory of that delicious tell-tale weed smell. To protect your girls, you must make smell a non-issue.

Here are the main ways to get rid of cannabis smell in your grow room:

• Carbon Filter/Scrubber (Best)
• Odor Neutralizers – Chemical method (Avoid)
• Masking Agents – Natural oils & things like incense (A bit effective)
• Air Purifiers – Works a little (Not the best)
• Ozone Generators – (DON’T USE!)

Best option: Carbon filter in a grow tent, like this setup (apparatus behind the LED at top-back of tent) – check out the grow journal!

In today’s “no smells in the grow room” tutorial, get up to speed on the options available to neutralize smells made by growing cannabis plants, and learn which methods are effective to…

• Cover up weed smell – Find a way to hide or cover up the smell. This can sometimes work for small plants, or a strain with a very mild cannabis smell.
• Filter the aroma (use filter to “scrub” weed smell from air) – Use a proven method to “scrub” the smells out of the air, typically using a carbon filter in a grow tent. #1 most effective method.

If you think about it, there are really only two real options when it comes to stopping smells in the cannabis grow room so no one can ever smell anything. Either hide or actually filter out the smell.

You could vent smelly air directly outside, which keeps smell out of the house, but neighbors can still smell marijuana when they come near. It’s best to filter the weed smell from air first. We don’t cover venting in this no-smell tutorial, but learn everything about stealthy venting here.

For a small grow with just 1 or 2 plants, you can sometimes get away with covering up the smell.

For a larger grow, you need to “scrub” the air in some way. Carbon filtering is the best way to ensure you don’t leak any weed smells to catch the attention of nosy neighbors.

Example no-smell cannabis setup (up to 11 oz harvest). Check out the grow journal.

1. Carbon Filter/Scrubber (Scrub odors from air)

These are hands-down the best option for controlling marijuana grow room odors. Carbon filters (also called ‘carbon scrubbers’) will actually pull the smells out of the air, neutralizing any odors that pass through.

Carbon filters are what you need if it’s important to neutralize the air coming out of your exhaust. A good carbon filter will make sure you never accidentally leak the smell of cannabis out through a window into your neighborhood.

These devices use activated carbon to chemically absorb smells and other impurities from any air that is pushed through the filter.

With a carbon scrubber, you need to set up a situation where the smelly marijuana air is being forced through the filter. In other words, you need to use a fan to push or (even better) pull air through the carbon filter.

The most common way to do this is to set up a carbon filter as a part of your exhaust system in a sealed grow tent, and use an exhaust fan pulling hot air away from your grow area. As hot air is pulled out and away from your plants, the carbon filter scrubs odors from the air on the way out.

Example of a carbon filter set up in a grow tent – this device scrubs all smells from the air so odors never leak outside the tent

Carbon filters are…

• highly effective
• extremely easy to maintain once they’ve been set up
• last a long time

How to Find & Install The Right Carbon Filter

1.) Identify the diameter of your exhaust

Many standard air-cooled marijuana grow lights are fitted with a 6″ exhaust hole (listed as 6″ air-cooled hoods). For most small-scale growers using a tent, you will want to get everything in 6″: including fan, carbon filter, and ducting.

Why 6 inches? 6″ fans are strong enough to exhaust the air from nearly any small-scale grow. Unlike 4″ fans which are often too weak for 4″ carbon filters & will not fit standard air-cooled grow lights. 8″ and bigger filters are generally for more commercial applications; they require extremely powerful (and expensive $$$) fans suitable to moving huge amounts of air from a large enclosed area, plus they can’t be hooked up directly to standard grow lights.

2.) Match up CFM rating between fan and carbon filter

Make sure the “CFM” rating of the carbon filter is the same or slightly higher than the one listed on your fan. This ensures maximum efficiency but also has an added security benefit: it makes sure your carbon filter is only taking in as much air as it can effective scrub for odors.

For example, if the carbon filter says “300 CFM”, your fan should be rated as 300 CFM or just a little lower. A 600 CFM fan would pull more air than the 300 CFM filter could deodorize.

Recommended 6″ Carbon Filter setup

Quiet option – For a smaller 2’x4′ grow tent (quiet fan), the Vivosun 6 inch smart filtration kit works great.

High Yield option – This Vivosun 6 Inch 390 CFM fan & carbon filter kit fits a bigger 4’x4′ grow tent (this has a louder but more powerful fan)

3.) Install fan and filter into exhaust system

Refer to the diagram below to see how a carbon filter should be set up in your exhaust system. The carbon scrubber being placed at the back of the exhaust system minimizes the risk of flowering cannabis smell escaping.

Learn more about setting up a grow light with an exhaust:
https://www.growweedeasy.com/hps-grow-lights-setup

Smell Emergency?

One trick to clear a room of smell that I’ve learned will work in an emergency is to put an exhaust fan on top of a carbon filter, and place it wherever the smell is strongest. I’ve done this when I’m cooking cannabis in the oven (which can smell up the house) or if I’ve been smoking and suddenly realized I have guests coming. It looks like this:

You don’t even have to attach the fan to anything, you can just let the scrubbed air go back into the room. It’s pretty amazing how fast this can clear up a smelly area! I learned this from a dispensary owner. Here is an example of a fan/carbon filter combo.

2. Odor Neutralizers (Use chemical means to cover up the smell)

Note: It is recommended you do not place these products in your grow room or tent with flowering cannabis plants. Strong odor neutralizers work so well they can actually reduce or alter the flavor of buds over time. However, these are incredibly effective at neutralizing odors outside the grow area.

Unlike a carbon filter, odor neutralizers don’t “scrub” the smells from the air.

These products are designed to bind with unpleasant smells so that the smell is “neutralized”. Often they also have a very strong fragrance to help cover up smells.

I’ve heard of growers using everything from incense to “bathroom sprays” to cologne to try to cover up the smell of a flowering marijuana plant.

Most household products like wall plug-ins and sprays just aren’t strong enough to cover up the smell of a marijuana grow room for long, if at all.

Also, using these products on your cannabis plants can reduce or alter their natural smell.

Any odor neutralizer or fragrance needs to be constant since your plants don’t stop making their unique flowering scent once they start. Once the smell arrives in your grow room, it basically keeps getting stronger until harvest.

However, there are a few heavy-duty products available that are effective for small-scale marijuana grow rooms.

Sprays, Glade Plugins, etc – Generally these are only effective for a few hours at most. Only recommended in an emergency!

Best spray to cover up smells in an emergency: Ozium Air Sanitizer – this smells very “citrus clean” that seems to do pretty well at covering up cannabis odor without smelling like you just sprayed a bunch of Febreeze. The only thing to keep in mind is a little bit goes a long way. A quick spritz is all you need!

I think the vanilla version smells better, but a little goes a LONG way.

Warning: Never spray any odor neutralizer near your plants in the flowering stage or the smell can stick to the buds!

Recommended Marijuana Odor Neutralizer – Ona Products

Ona Gel and Ona Blocks were originally developed to control the smell inside sewage facilities. They are now available to consumers because they are remarkably effective at neutralizing odors.

Ona products are quick and easy to use. They are effective at covering up smells in a small grow room, though they will only work for a relatively short window of time and must be replaced every few weeks up to a few months.

Ona Gel in the original scent seems to be the most effective for covering up marijuana smells in our tests. With a few flowering plants in a grow tent or closet, you will be able to cover up almost all smells with one or two of these placed outside the grow room.

Never place Ona products in with your flowering plants!

If you use Ona products in your living room, den, or other open areas, no one who enters those rooms will be able to smell any sign of your cannabis plants, even if the plants are just a room away.

But Ona products can reduce or alter the smell of your cannabis buds if they share the same air, so you should never place Ona products in the same area as your flowering plants.

If you need to neutralize the smell coming out of your exhaust, a carbon filter (#1 on this list) is highly recommended. You could also have your exhaust air blow over an Ona product right before being vented outside. It is not recommended to use Ona products in your grow area alongside your plants. Ona products are meant to be used outside the grow area.

PSA: Don’t use ONA to control smells IN the grow room

How long do they last? It depends on the size Ona Product you buy, as well as the temperature/humidity of your grow area.

Generally, they seem to last at least 4-6 weeks for most growers, which is long enough for a few of these to provide coverage throughout the smelly second half of the flowering stage.

Ona Gel Pro

(stock up on these to make sure no one can smell cannabis in your home)

3. Masking Agents – Natural oils & things like incense (A bit effective)

These are the types of things you might already have around the house to improve/change the smell.

• Essential oils – somewhat effective, but only can effectively cover up very small smells. Otherwise you just have the smell of weed mixed with the essential oil.
• Perfume / Cologne – Even less effective, and it seems weird for a room to smell strongly of a personal scent, so not the best choice.
• Incense – Usually more effective than essential oils, especially the really strong/smelly incense. “Patchouli” scented incense (and others) can be powerful stuff. The bigger issue with incense is that the smell of incense itself can be bothersome for some people, especially if you burn enough incense to cover up the smell of a cannabis grow operation.
• Scented candles – Less effective than essential oils, typically. Usually you get a “weed plus the candle” kind of smell.

The strongest (and cheapest) incense is usually found at a head shop (bong shop) or local market. Online incense tends to smell much weaker.

4. Air Purifiers (Air Filters)

We all love the idea of having pure air to breathe. Many air purifiers come with the claim of reducing smells, usually by means of a filter. Do these work to get rid of smells in a marijuana grow room?

Not really.

It is true that some air purifiers do help remove some smells from the air. However, these are not strong enough to pull all the smells from a grow room.

A regular air purifier only removes a little weed smell (marginally effective)

Therefore, while air purifiers may be a good choice for other reasons, I do not recommend getting one just to try to get rid of smells in your cannabis grow room.

But it never hurts to keep one near the front door so everything always smells super fresh when you open your door.

I have the following ridiculously expensive air purifier, which I keep near the front door. I originally got it for allergies, which it helped with a lot (If anyone else struggles with allergies, it worked well enough I got a second one for the bedroom). But unlike other air filters I’ve tried, it actually does a pretty good job of removing weed smell, too.

Yet even this industrial air purifier has nothing on the cheapest carbon filter to get rid of weed smell!

5. Ozone Generator – DO NOT GET ONE!

Ozone generators are sometimes added to grow rooms to neutralize smells. Ozone generators claim to remove odors, clean the air, and kill mold and mildew.

Although some growers claim that ozone generators are the best means of eliminating odor, at GrowWeedEasy.com, we strongly recommend against having one in your grow room.

What’s the big deal?

Well, ignoring the fact that Ozone is not as effective as a carbon filter at reducing odors, one problem is that they’re bad for the environment. So much, in fact, that they’re illegal in the state of CA where I live (see: http://www.arb.ca.gov/research/indoor/o3g-list.htm).

More importantly, ozone generators are actually bad for YOU!

Here are just a few of the many links to research from reputable institutions all saying the same thing: Ozone generators are bad for humans!

• EPA (U.S. Environmental Protection Agency)
  • “When inhaled, ozone can damage the lungs.”
• OSHA (U.S. Occupational Health & Safety Administration)
  • Ozone is listed as a “Major Indoor Air Contaminant”
• American Lung Association
  • “Ozone is a potent lung irritant and exposure to elevated levels is a contributor to the exacerbation of lung disease”
• California Air Resources Board
  • BANNED!
• Texas Department of State Health Services
  • “Ozone-generating devices should not be used in occupied spaces. Ozone is a lung irritant.”

Some growers claim to have safer ways to use ozone in their grows, such as venting ozone out of the house or making sure ozone only goes into the exhaust. Again, we would strongly recommend against using ozone since in the best case, it’s only doing what a carbon scrubber can do. In the worst case, it’s hurting the lungs of you, your pets and your family!

Make Sure Only YOU Get To Enjoy Your Plant’s Smell!

Start growing a Low Odor Marijuana Strain today!

These strains produce neutral, non-marijuana-like odors… even as they approach harvest!

1.) Frisian Duck

Frisian Duck is the quintessential stealthy, low odor strain. Frisian Duck was designed from the beginning to be a “stealth strain” by the breeder Dutch Passion, who has continued to maintain and improve the strain. Frisian Duck gives you purple buds, duckfoot-shaped leaves, and a mild smell of spicy pine

On “duckfoot” strains like Frisian Duck, the leaves don’t look like regular cannabis leaves! Purple buds with a mild, spicy pine scent.

Where to get Frisian Duck seeds:

• North Atlantic Seed Co. (Maine, US)
• Seedsman (US, UK & Europe)

2.) Blue Mystic

Blue Mystic was originally designed by Nirvana and then Royal Queen Seeds took the mantle with their version. This strain tends to stay short, the buds get big, and the smell stays mild.

Where to get Blue Mystic marijuana seeds:

• North Atlantic Seed Co. (Maine, US)
• Seed Supreme (California, US)

Blue Mystic is a famous low-odor marijuana strain that stays short and produces high quality buds.

3.) Blue Sunset Sherbert

Buds that grow on Blue Sunset Sherbert plants by Barney’s Farm tends to have a lighter, sweeter smell than most cannabis buds, and lack the distinctive “skunk” odor.

Where to get Blue Sunset Sherbert cannabis seeds:

• North Atlantic Seed Co. (Maine, USA)
• Seedsman (US, UK & Europe)

Blue Sherbert Sunset grows with a relatively low cannabis smell, and produces pretty, potent buds up to 28% THC.

Special mentions

Photoperiod strains

Jump to…

How to Set Up Your Grow Lights – Step-By-Step Tutorial

Stealth Growing: How to NOT get Caught Growing Weed

7 Rules You Must Follow If You Want to Grow Weed and Never Get Caught

How (and Where) To Buy Marijuana Seeds

The post How to Control Smells & Odors in the Cannabis Grow Room appeared first on Grow Weed Easy.