How to Grow Marijuana – Lesson 4a – Deep Water Culture


Welcome to Hydroponics

Today, we start you on your journey with hydroponics marijuana cultivation. There are many benefits to using hydroponics over soil growing, such as:

  • Higher yield
  • Faster, more aggressive growth
  • More precise feeding
  • More control
  • More fun

There are also a few downsides to hydroponics, like:

  • Inability to grow outdoor
  • Susceptible to power outages
  • Volatility of pH

Don’t let the downsides ruin the experience for you, however, because the benefits far outweigh them.

We are choosing the simplest method for your first hydroponics system, Deep Water Culture.

Deep Water Culture, or DWC, is simply growing your plants suspended over a bucket of water and nutrients. In order to ensure maximum air delivery to the root zone, as well as eliminate stagnation of the nutrient solution, an air pump and air stone are installed.


What You Will Need

It would be a good idea to go to a few restaurants and ask for five 2-gallon buckets and five 5-gallon buckets (more on that later). Buying your buckets will cost quite a bit, but a hardware store would be your best bet. Buckets online are expensive. Starting with 2-gallon buckets will save you on nutrients when your plants are small and have very little root growth.

Other than the buckets, you will also need four net pots, a good water filter, a substrate (we like expanded clay pebbles), aluminum foil, an aquarium air pump and four air stones. You can find all of these on our What You Need To Grow Marijuana page.

Keep in mind that this tutorial is only for the hydroponic system and you will require a place to put it (grow tent), lighting, ventilation and timing devices. There are other optional systems, such as our simple Carbon Dioxide Generator.


Buckets and Baskets

2-Gallon buckets (for now) and 5-inch net pots, 4 with lids, 1 for water changes


Air Stones

Air Stones (bigger is better as long as they fit in the bucket)


Hydroton

Expanded Clay Pebbles (Hydroton)


Drill With a Bit the Same Size as the O.D. of the Air Tube

Electric drill with the same size bit as the O.D. of the air tubing


Aluminum Foil

Aluminum Foil cut to the inner diameter of the bucket lids


Utility Knife

Utility Knife


Non-recirculating

We chose to make our buckets not the recirculating type (extra reservoir, water pump, buckets all connected) for a variety of reasons, including:

  • Zero chance of unexpected leaks
  • No extra power for the water pump
  • No buying or replacing the water pump if it burns out
  • Easier to pinpoint water problems
  • Water problems don’t affect every plant
  • Cheaper for nutrients
  • Less likely to have toxic salt buildup (Buckets are well cleaned every water change, changed more often)

Recirculating is excellent for less frequent water changes and for people who cannot check on their plants as often, but this is not the case with our particular situation.


Soaking The Hydroton

Measure hydroton that you will be using by filling one of the net pots four times and dumping it carefully into one of the five buckets you have. Add filtered water until they are slightly covered.


Soaking Clay Pebbles

Hydroton soaking in filtered water


This will serve two purposes: helping to rinse sediment off of the hydroton, and partially saturating the pebbles to make water transfer better when you plant your seedlings. Continue soaking them while building the rest of the system, and move them around with your (CLEAN!) hand periodically.


Preparing The Lids

The next step is the most complicated and most important that it is done right. Cutting too much can cause the net pots to fall through or too big of a hole for the air tube can cause other problems and you want all the air being sent through the air stones to exit the bucket through the growing medium (hydroton in this case).

The Net Pot Holes

The first step to preparing the lids is to plan. If the lid doesn’t have something telling you where the centre is, then you will need to find it and mark it. From there, you will want to draw two concentric circles: one the size of the bottom of the net pot or slightly smaller and one the size of the top of the net pot or slightly larger (one or two millimetres).

This is easy enough to do. Just trace the net pot with a pencil or permanent marker.


Net pot tracing

First, trace the bottom of the net pot


Net pot tracing

Then trace the top, making sure they are both centred


Circles drawn

Circles are drawn and ready to cut


Once the circles are drawn, the next step is to cut out the inner circle very carefully, using the utility knife.


Middle cut

Middle hole cut out


Once the middle circle is done, the outer ring will be used as a guide for the next step.

Make a series of cuts from the middle to the outer ring, but do not pass the line. They should be all the same size, about a centimetre or half-inch apart.


Flaps

Flaps are cut and the lid is ready for the net pot


Once the flaps around the entire circle are done, these small flaps will help to keep the pot snug and secure, so it won’t move or fall through while your plants are growing.


Stabilizer flaps

The flaps keep the net pot from moving or falling through


Put the lids on the buckets and grab the drill. It’s time to make the hole for the air tube. You will want to make the hole half-way between the edge of the bucket and the flaps.


Buckets ready for air tubes

Ready to drill the holes (you shouldn’t have pebbles in the baskets yet, it’s just there for the picture)


Air tube holes are drilled

Air tube holes are drilled and the buckets are ready for the air stones


Preparing The Hydroton And Air Stones

Before adding water or growing medium, wipe all hard surfaces with Lysol wipes and rinse very well. You do not want mould spores in your grow area.

When soaking and rinsing, you want to use filtered water, just like you would use in your system for your plants. Contaminants can stay in porous surfaces when you don’t want them to, so keep your growing system clean right from the start.

Your clay pebbles should be well soaked by new and will need to be rinsed a few times. To do this, fill a net pot and pour filtered water over them.

Next, rinse your air stones or set them in filtered water to soak.

Decide how long your air tubes need to be to reach the air pump where you want to have it. The pump needs to be above the water level at all times unless you have a check valve in each line (check valves are expensive and it is easier just to keep the pump above).

Cut the air tube to appropriate lengths and attach the air stone to one end. Put the other end through the bottom of the lid.

Now, your buckets are ready for the clay pebbles.


Tube and air stone in place

Air tube and air stone in place


First bucket done

The first bucket is done, the second one almost


Plant Your Seedlings and Feed Them

The buckets are ready to have either just filtered water or nutrient solution added (to keep the clay pebbles from drying out if you aren’t planting immediately) and seedlings to be planted. Even if you aren’t planting right away, you will want to run the air pump as if you did, to ensure the water doesn’t become stagnant.


Seedling planted

A seedling planted in new DWC bucket


Do your best to plant your seedlings in the very center of the net pot, as it will make the next step much easier.

The aluminum foil that was cut to the inner diameter of the bucket lid will need a slit cut from one edge to the center, so fold it in half twice and find cut along one fold.


Aluminum foil substrate cover

Aluminum foil to cover the clay pebbles


Then, you will make four small cuts like an “X” from the center out about a half-inch or a centimetre each. Fold the small flaps you made to make an opening for your seedling.


Seedling hole

Flaps folded open for a seedling to grow through


Guide the stem of the seedlings through the slit to the opening and tape the aluminum foil circle down so that your circulation fans don’t disrupt it.


Completed DWC System

DWC Bubbler bucket completed and planted


The foil will keep the light reaching the substrate and nutrient solution to a minimum, vastly reducing the chance of algae growth, and keep as much moisture as possible from evaporating out of the clay pebbles instead of being taken in by the roots.

Congratulations!

You now have a complete hydroponics system!

Happy Gardening!