Common Growing Questions: Answered!

by Nebula Haze

Table of Contents

Getting Started

  • Is it hard to grow weed?

  • Where can I get seeds?

  • Can I stick a seed in soil and watch it grow?

  • How can I tell if a seed is good?

Plant Problems

  • What if my plant runs into problems?

  • How do I get rid of gnats flying around my soil?

Soil & Growing Mediums

  • What kind of soil should I get?

  • What about growing in coco coir?

  • What type of container should I use?

  • How do I get started with hydroponics?

Cannabis Nutrients & Supplements

  • Do I need special nutrients to grow cannabis?

  • Is pH really that important?

  • Can I use tap water?

  • Can I grow cannabis with Miracle-Gro?

  • Do “finisher” additives (sugar, molasses, ‘big bud’ type additives) work?

  • Which nutrients make the biggest buds?

Cannabis & Light

  • How much light do I need?

  • Which LED grow light is the best?

Increase Yields

  • What’s an easy free way to increase yields indoors?

  • Do CO2 Bags work?

  • Does "defoliation" (plucking leaves) help or hurt growth/yields?

  • Is it worth it to "re-grow" a plant after it's been harvested?

Gender & Life Stages

  • How long until plants start making buds?

  • Why do growers want female plants?

  • Where do I look to tell the sex of a plant before it starts flowering?


Getting Started

Is it hard to grow weed?

No! It’s really easy once you know what to do! Read the simplest basics guide ever!

Where can I get seeds?

You can order seeds online. You can also grow seeds you find in your bud, though just remember they don't always grow "true" and may not end up the same as the buds they came from!

Can I stick a seed in soil and watch it grow?

Yes, kinda. The cannabis plant is a weed and it can sprout and grow in a lot of conditions.

But if you want to get decent yields and quality bud, you must give your plant what it needs, especially during the budding stage.

At the very least, it’s important to provide cannabis plants with water, nutrients and a lot of bright light! Remember that light is like food to your buds; buds won't get fat unless you give them a lot! Learn about different grow lights.

How can I tell if a seed is good?

Germinate your seed. If it grows, it’s a viable seed!

Sometimes relatively pale or fragile seeds can grow into the best plants. You can’t tell the quality of a seed just from looking at it. If in doubt, order seeds of proven strains from a reputable cannabis breeder. That's the only way to ensure you get the best bud quality, yields and effects! The difference in results between strains can be pretty astounding!

Here are what viable marijuana seeds look like. Did you know the stripes are actually part of a protective coating that can be rubbed off? The slightly more pale seed in the picture below is an example of what a seed looks like without its stripes 🙂

Cannabis seeds - ready to plant!


Plant Problems

A discolored cannabis leaf suffering from a deficiencyWhat do I do if my plant runs into problems?

Look at pictures of sick plants and get solutions! Or go through our 7-Step Fix to 99% of Plant Problems!

How do I get rid of fungus gnats?

Fungus gnats are tiny annoying bugs that buzz around your soil and look like little flies. You can use insecticide to kill them, but fungus gnats are usually a sign of a separate problem: the top layer of your medium is too wet for too long at a time.

When you're suffering from gnats, make sure you only water when the top inch of your medium is dry, and don’t drench it. With good watering practices, fungus gnats simply can't reproduce and disappear.

Learn about fungus gnats as well as other bugs and pests!


Growing Mediums

What kind of soil should I get?

Cannabis seedling in soil - in handsAny quality organic potting soil can work. Don’t get soil with time-released nutrients (like Miracle-Gro soil) and don’t use dirt you find outside.

If you’re looking for a specific brand for growing cannabis, a lot of people like Fox Farm soil. If that’s what you choose, you might consider starting with Fox Farms Happy Frog soil mixed with about 20% perlite for a great cannabis soil starting mix. Some growers prefer to use "living" soil, so they don't have to add any extra nutrients in the water.

Learn about the types of soil that are good for growing cannabis.

Some growers use a soilless growing medium or potting mix, for example coco coir…

What about growing in coco coir?

Growing in coco coir is a simple type hydroponics that gets faster growth and bigger yields than soil. But since coco coir grows can be hand-watered, it feels a lot more like growing in soil than hydroponics. Learn how to get started growing cannabis in coco coir.

Here's a complete tutorial that will show you how to use a small 250W light and coco coir to harvest 4-7 ounces. This is how I recommend starting your first grow! It's easy, gets great yields, and prepares you if you want to try soil or hydroponics down the road.

A young vegetative cannabis plant growing in coco coir

Smart pot (fabric container for growing cannabis)

What type of container should I use?

Any plant container should work. For the easiest growing, I personally recommend getting a smart pot (a growing container made out of fabric). That’s what I use. They deliver more oxygen to the roots to help increase growth and prevent problems like overwatering.

Learn more about different cannabis growing containers.

How can I get started with hydroponics?

Learn about the different hydroponic methods and jump right in! Here's a tutorial on how to grow with bubbleponics.


Cannabis Nutrients & Supplements

Do I need special nutrients to grow cannabis?

Fox Farms nutrient trio is a good nutrient system for growing cannabisYes and no. Cannabis plants have two stages of life and it is important they get the right nutrients at the right time. When using liquid nutrients, use a “Grow” nutrient formula for the first stage of life, and a “Bloom” formula when buds are forming.

Nutrients from the store can be used, but many growers believe you’ll get the best results by using a cannabis-friendly nutrient system.

Here are NPK ratios to help you pick the right nutrients if you can't get one that’s specifically formulated for a plant like cannabis. “N-P-K” are the three numbers listed on every nutrient bottle.

Chart diagram showing the optimal NPK nutrient ratios for growing cannabis or medical marijuana

  • Vegetative/Grow – High N, Medium P, High K.
  • Bloom/Flower – Low N, Medium or High P, High K

Note:  Don’t use anything with time-released nutrients like fertilizer spikes, or Miracle-Gro soil – they deliver too much N in the flowering stage.

Learn more about cannabis-friendly nutrients.

I don’t pay attention to pH, but I keep running into nutrient problems. Is pH really that important?

Yes! Managing pH is the #1 way to prevent nutrient deficiencies when using properly formulated liquid nutrients. Some growers get lucky, but if you're seeing nutrient deficiencies the first thing to do is check the pH.

Can I use tap water to water my plants?

Water coming out of a faucet

Cannabis plants are not that picky about water as long as your nutrients are right and there's not too much salt. Many growers can use their tap water. If your local tap water is toxic to plants and can’t be used, you can use filtered or RO (reverse osmosis) water. If using RO water, make sure to supplement with a CaliMagic (calcium & magnesium) supplement to make up for the lost minerals that normally come in tap water.

Can I grow cannabis with Miracle-Gro?

Here’s a question: why don’t you brush your teeth with baking soda? Baking soda definitely works, but the problem with it is that we already have something much better that’s more specialized to do its job.

Miracle-Gro can grow cannabis pretty well the vegetative stage, but it has slow-release Nitrogen that gives too much Nitrogen in the flowering stage, possibly supressing bud growth. It also has just-okay drainage. Although you can make it to harvest with Miracle-Gro, why not use something that’s meant to do this job?

In short: Get some soil and nutrients that works well for cannabis. It’s worth the few extra dollars!

Do “finisher” additives (sugar, molasses, ‘big bud’ type additives) work?

They probably won’t hurt your plant, and they may help, but there’s not a lot of real evidence either way for many types of supplements (at least not yet!).

Learn which nutrients and supplements actually increase bud quality!

Which nutrients make the biggest buds?

This is a trick question. Nutrients keep plants healthy, but light makes buds. You need nutrients to prevent nutrient deficiencies, just like humans might need a multivitamin.

As long as your plant is healthy, you will generally increase yields by providing all parts of the plant with enough light. This is easier with plant training. Light is like “food” for your plants.

Learn everything you need to know about maximizing cannabis nutrients!


Cannabis & Light

How much light do I need?

Cannabis plants need bright light... but not too brightOutside your plant needs 8+ hours of direct sunlight a day for the best results. The less light your plants get, generally the lower your yields.

Indoors, you need bright grow lights to get cannabis to produce a lot of bud, but smaller lights can also be used to produce great cannabis – just in smaller amounts.

Growing practices like plant training can often dramatically increase yields indoors. Using your indoor grow space wisely can make the difference between harvesting 4 ounces or harvesting 16 ounces in the exact same setup.

Learn about what yields to expect with different grow light setups

Should I get LED grow lights? Which model is the best?

Cannabis plants under an LED grow light in a grow tent

LEDs can grow great cannabis, but there are many sellers who make bold, untrue claims about what LED grow lights can do.

LEDs are efficient light sources and come with built-in fans, which can make it easier to disperse heat in a small space, but they’re not magical. If a claim sounds too good to be true, it probably is!

The simple fact is that most LED grow lights DO NOT consistently produce bigger yields than a HPS grow light of the same wattage (at least not as of the year 2017). That being said, LEDs do have other unique benefits like the ability to create a custom light spectrum, and some of the "Spydrx" style LEDs seem to be getting better yield and quality results with cannabis than any previous models of LED! The only problem is they're expensive!

Learn more about which LED grow lights work for growing cannabis!

For those who want to stay on the cutting edge of technology, there's another newly popular type of grow lights called "LEC grow lights" which seem to be consistently beating LEDs for yields and ease of use. If you go to a hydroponics store you no longer see LEDs on the shelves, just T5s, MH, HPS and LECs! If you're not sure what to get and are shying away from HPS, I highly recommend LECs over LEDs! Learn more about LEC grow lights.


Increasing Yields

What’s an easy free way to increase yields indoors?

Master plant training so it's easier to get light to all parts of your plants. Keep grow lights the correct distance from the top of your plants. Generally you want to keep indoor grow lights as close as possible without causing heat problems or light burn.

Cannabis yield - buds in mason jars

Do CO2 Bags Work to Increase Growth and Yields?

Maybe. They won’t hurt your plants, but it's relativaly unlikely your plants will grow significantly faster since they often don't put out a whole lot of CO2. Learn how to do CO2 right.

Does "defoliation" (plucking leaves) help or hurt growth/yields?

It's an understatement to say there is a lot of controversy about defoliation. Some growers swear it increases yields, others swear it actually hurts yields. Most people agree that first-time growers should not pluck a lot of leaves unless their plant is overly bushy.

As for my experience, I have gotten good results with defoliation in the flowering stage to expose bud sites in the flowering stage, especially on leafy plants. It's not as effective if bud sites are already exposed, or if plant is not particularly healthy and leafy. Here's how I do defoliation.

Is it worth it to Re-Veg?

Is it worth it to "re-grow" a plant after it's been harvested?

Re-vegetating means harvesting a plant, leaving some green growth left, then switching the plant back to the vegetative stage for a second smaller harvest. Seems good on paper, but this technique gives you much less control of your plant in addition to more time taken and smaller yields. Every grower I know who's tried re-vegging has said it works, but they'll never do it again.

Short answer: It works, but it's not worth it!

Learn more about re-vegging weed plants


Cannabis Gender & Life Stages

You can grow cannabis like this, too!How long until plants start making buds?

Cannabis starts making bud in the flowering stage (the second stage of life). However, nearly all cannabis plants need to get 12 hours of darkness each day to be in the flowering stage. After being put on a 12/12 schedule, most plants start growing buds within 1-3 weeks. Learn more about cannabis life stages.

How long does it take to grow weed?

Why do most growers want female plants?

Only female plants make buds. Learn more about male and female cannabis plants.

Can tell the sex of a plant before it starts flowering?

Yes, there's a few different ways, and new technology lets us determine gender sooner than ever!

First there is chemical leaf testing you can pay for. By sending in a small sample of your leaf (for example a cotyledon or a punchout from a leaf) you can test for the gender of your plants as soon as 1-2 weeks from germination!

As far as just using your eyes, you won't be able to see anything indicating sex on the plant until at least week 3, and probably it will take a few weeks longer before you'll be able to tell visually.

Learn how to determine gender while marijuana is still in the vegetative stage!

You can also wait until the plant starts flowering to separate males from females, because at that point their gender will be obvious! 

Or, if you don't want to worry about gender at all, you can start with clones or feminized seeds (so all the plants end up female)! Learn more about feminized seeds. 



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