Hydroponic Cannabis Growing: How It Works and a DIY Setup Step by Step

How to grow cannabis hydroponically

What is hydroponic cannabis growing?

Hydroponic cannabis means growing in an inert medium like coco, or straight in a water reservoir, with every nutrient the plant needs delivered directly through the water. In other words, the weed grows in a solution of water and nutrients instead of soil. You can buy a hydroponic starter kit with everything you need, or build your own setup by hand.

Growing in coco coir counts as a type of hydroponics, since coco naturally contains no nutrients and you have to supply all of them through the water.

The ideal pH for coco and hydro is 5.5–6.5, while the ideal pH for soil is 6–7. In hydro, you have to start feeding nutrients from the seedling stage (at seedling-strength doses to begin with); otherwise the seedling grows more slowly, because all it has is what's stored in the seed itself. In soil, you don't need to add nutrients for the first few weeks, since the soil already has some.

Step one is picking a growing medium that holds up the spot where the stem meets the roots. You can use clay pebbles, which keep the root system airy. If you go this route, you'll need to adjust the pH of your water and get a plastic hydro net pot with holes for the roots to grow through. Another solid option is rockwool, which holds a lot of water and keeps the roots well hydrated. Perlite is a good alternative too, with a moisture retention of around 63%.

To move water around, you can use a wick system, which works with clay pebbles and doesn't need a pump: water travels up the wicks and keeps the medium moist. The nutrient film technique (NFT) puts plants in a sloped tube where water enters at one end and drains out the other, keeping the roots wet inside the tube. Deep water culture (DWC) is the simplest method: plants sit in buckets filled with nutrient solution while an air pump keeps it oxygenated.

Plants in hydro setups generally grow faster in veg than soil-grown plants and are less prone to mistakes. Plus, the buds can feel more potent. You also get much tighter control over nutrient levels, PPM (parts per million, a measure of how concentrated your nutrient solution is) and pH.

Plants grown in a hydro reservoir tend to grow faster during veg, which means bigger yields and quicker harvests. Hydro buds also tend to be more potent and often fetch higher prices in places where selling dried flower is legal.

Once a hydro reservoir is set up, it doesn't take much time or work to keep it running. Instead of watering your plants on a schedule and dumping runoff, a hydro reservoir just needs you to dip in a pH pen and top it up with water or tweak things as needed.

Unless you protect the roots with the right supplements and gear, your plants can run into root rot. The scariest part of hydro is really just getting started; after that, the plants are honestly pretty easy to look after.

What are the main hydroponic growing methods?

There are several hydroponic methods, including:

1. NFT (Nutrient Film Technique): This system uses sloped channels with a thin film of nutrient solution flowing through them, bathing the roots of the plants suspended in the channel.
2. Floating raft system: Here, plants sit in a raft that floats on top of the nutrient solution. The roots hang down into the solution while the plant itself stays suspended above it.
3. Drip system: This setup uses a network of tubing with drip emitters that deliver nutrient solution to plants in pots or containers.
4. Aeroponics: The plants' roots hang in the air and get sprayed with a fine mist of nutrient solution.

How you start a hydro grow depends on the system you're using. Generally, you begin with seeds or seedlings placed in a sterile growing medium like rockwool or coco coir. Then the roots go into the nutrient solution and stay in the hydro system until the plants are ready to harvest.

How to build a DIY hydroponic system, step by step

What you'll need:

• A plastic container with a lid (a storage tote or something similar)
• Plants or seeds
• Growing medium (like rockwool, coco coir or perlite)
• Hydroponic nutrient solution
• Tubing or hoses
• Water pump
• Air stone with an air pump (aerator)

Instructions:

1. First, pick a plastic container with a lid that's big enough for the size of the plants you want to grow. Make sure the lid seals tight.
2. Cut holes in the lid where your plants will go. They need to be big enough to fit your plants or net pots.
3. Put the growing medium in the net pots. You can use rockwool, coco coir or perlite. Fill the pots halfway with your medium of choice.
4. Set the plants or seeds into the pots with the growing medium and place them in the holes in the lid. Make sure the roots are in contact with the medium.
5. Mix the hydroponic nutrient solution in a separate container. Follow the package directions for the right water-to-nutrient ratio.
6. Connect the tubing or hoses to the water pump. Put the pump inside the container and make sure it's fully submerged in the nutrient solution.
7. Connect the air stone to the air pump. This oxygenates the nutrient solution and keeps the roots healthy.
8. Seal the lid of the container tight.
9. Turn on the water pump and make sure the nutrient solution is circulating properly through the tubing.
10. Put your hydro system somewhere it gets enough light and where temperatures don't swing too hot or too cold.