How to Grow Hydroponic Cannabis at Home

by Nebula Haze

Hydroponics is when you grow your cannabis plant in an inert medium like coco or a reservoir of water, and provide all the nutrients to the plant directly in the water.

Growing in coco coir can be considered a type of hydroponics since it naturally contains no nutrients and you must provide all the nutrients in the water. However, when you say “hydroponics” most people think of this:

Example of two happy vegetative marijuana plants growing in DWC hydroponic tubs

When it comes to hydroponic cannabis…

Differences Between Soil & Hydro

  • The optimum pH for coco and hydroponics is 5.5-6.5, while the optimum pH for soil is 6-7
  • Nutrients must be provided from when a hydroponic plant is a seedling (in seedling doses to start), otherwise the seedling will grow slower because it only has what’s contained in the seed itself. In soil you don’t need to add nutrients for a few weeks since there’s already some in the soil
  • Growing in coco coir (a growing medium that looks somewhat like soil but is actually made of dried coconut husks) gives you results that are somewhat between growing in soil and growing in a hydroponic reservoir of water – you get a lot of the benefits of both

Pros of Hydro

  • Plants in hydroponic setups generally grow faster in the vegetative stage than soil-grown plants
  • Less likely to get bugs
  • Buds can feel more potent
  • If growing in a reservoir you don’t have to worry about watering your plants when they’re dry, over/under watering, or removing runoff. Everyone is different but I find maintaining a hydro reservoir easier than moving the plants around or watering and using a wet vacuum to remove runoff (but we all have our personal preferences!)
  • If growing in a reservoir you use a very efficient amount of nutrients since you only mix up new water a few times a month, and only toss old water after the plant has already used up a lot of nutrients, which can save quite a bit if you’re using expensive nutrients and is better for the environment (compared to drain-to-waste)
  • You have more control over nutrient levels, PPM, and pH – for the mad scientists among us who want to get the most out of our plants as possible!

Cons of Hydro

  • Hydro usually takes more preparation/setup than growing in soil. You’re providing more for the plant instead of letting the soil do some of the work for you
  • It can be easy to get root rot in hydro if you don’t provide your plant with a good-bacteria supplement like Hydroguard.
  • Soil-grown buds may have a more complex or stronger smell than hydro-grown buds, especially if grown in composted living soil without any liquid nutrients
  • Growing in soil is more intuitive for many people, and some people already have experience with soil from other types of gardening!

Is Hydroponics Good for Growing Cannabis?

Have you seen cannabis plants growing with their roots just floating in a reservoir of water? This type of hydroponics is known as Deep Water Culture (DWC), and has been around for over a 100 years! As more growers gain experience with this medium, DWC has become increasingly popular for growing cannabis. Hydroponic setups are really neat and offer some big benefits over growing in soil!

Benefits of Hydro Over Soil

  • Plants grown in a hydroponic reservoir tend to grow faster in the vegetative stage, resulting in bigger yields and faster harvests
  • Hydroponic buds tend to be more potent and often cost more at dispensaries
  • Once a hydroponic reservoir is set up, it does not take a lot of work or time to maintain. Instead of regularly watering plants and removing runoff, a hydro reservoir only requires you dip a PH Pen and top off with more water or adjust as needed.

Cons of Hydro

  • Takes more time and effort to set up than soil or coco
  • Buds grown in soil without added nutrients tend to have a stronger smell than buds grown with liquid nutrients like in a hydroponic setup (though if you’re trying to keep things low odor this might be a benefit).
  • Unless you protect your roots by using the right supplements and equipment, your plants may struggle with root rot. Luckily if you follow the steps in this tutorial you don’t need to worry about root rot killing your plants!

Hydro is a no-brainer for me. Whenever I go back to a hand-watered grow like coco coir, I am always surprised by how much extra time it takes to water plants and remove the runoff. The most intimidating part of hydro is just getting started – after that it’s actually really easy to take care of your plants. In my opinion, hydro is far easier and less time consuming than growing in soil or coco coir once you’re set up. If you are interested in hydro, go for it! If you follow this tutorial you will succeed!

Today I’ll teach you how to set up your hydroponic reservoir for growing cannabis, and I’ll show you what you need to do each day for optimum growth 🙂

How to Grow Cannabis in DWC

Supplies & Gear

So there are five major parts to getting set up. You need….

  • Grow Environment – I personally recommend a grow tent as opposed to building your own environment from scratch.
  • Grow Light – If you don’t already have a grow light, I recommend getting a 250W400W or 600W HPS grow light for your first grow. They are the most consistent type of grow light and get really great results in DWC.
  • Nutrients – I highly recommend getting GH Flora trio, Cal-Mag and Hydroguard.
  • Seeds – Learn where to get seeds
  • DWC tank – Learn how to build your own

If you don’t want to build your own, it’s possible to buy a DWC tank (hydroponic bubbler) online though they’re less common than you’d think! The closest DWC tank I’ve seen for sale online at Amazon.com is this one. I cannot personally vouch for the vender, but as of this post the seller has a 100% approval rating. So although I can’t truly recommend this bubbler, it is the one I would get if I was going to purchase one (instead of making one myself).

Example of a hydroponic bubbler (DWC tank) that you can buy online at Amazon.com

Get a large airstone on Amazon to make lots of bubbles!Get a large airstone on Amazon to make lots of bubbles!3/16" Flexible Airline Tubing for Aquariums

Once you’ve got your gear and supplies, it’s time to get set up and start growing!

Seedling Germination & Daily Care

  • Set up reservoir – Water, seedling nutrients & pH. Make sure to add beneficial bacteria
  • How to start seedlings – Make sure top feed is not butted directly against Rapid Rooter
  • Top off reservoir regularly with nutrient water. In order for the beneficial bacteria in your reservoir to make a strong, healthy colony it helps to avoid doing a complete reservoir change for the first 3-4 weeks. Instead, top off your reservoir with vegetative strength nutrients when the water level gets low. This will slowly raise your nutrient levels from seedling to vegetative stage strength without stressing your plants, and giving your root colony as much a chance as possible to get established on your roots before you completely change the water.

Vegetative Stage

  • Choose best plant(s) if necessary
  • After first 4 weeks, completely change reservoir every 1-2 weeks.
  • How to train with ties
  • Switch to flower when plant has reached half the final desired size

Flowering Stage & Harvest

  • Switch to 12/12
  • Consider light defoliation
  • How to stake up big buds (yo-yos or stakes)
  • Lower nutrients after week 6-7
  • Harvest

Solutions to Most Common Problems

  • Root rot
  • Nutrient deficiencies
  • Nutrient burn

 

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