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Bob ILGM

April 16, 2019

Deep Water Culture for Cannabis

The Deep Water Culture (DWC) is a simple yet effective hydroponics system that soaks the plants’ roots directly into an aerated nutrient solution. The DWC system is effective for growing marijuana. On top of that, it’s easy to construct and operate.

One of the advantages of a DWC grow is that the roots of marijuana plants love oxygen. A DWC system allows the roots of plants to become permanently suspended in a solution filled with nutrients. An air pump instills oxygen into the solution thereby providing the plants with the oxygen they require. As the roots of the plants grow downwards into the nutrient solution.

When growing using the DWC, the roots don’t need to spread out and they don’t have to search for nutrients in the soil because everything the plant needs is readily available. This decreased effort in having to “find” nutrients translates to increased growth and thicker foliage especially when couple with plenty of light.

Buds will fatten up more in the flowering stage but that doesn’t mean the harvest period would be any faster. The time to harvest will still be dependent on the strain.

This grow journal records growing Serious Seeds using the DWC system.

Grower: GreenMachine
Yield: 8 ounces
Location: NA

September 5th

This grow journal starts with some Serious Happiness seeds already in the net pots. Since the plants have been in there too long, their roots have started to grow through the net pots.

The plants are inside this grow tent. One of the ribs in each net pot was cut to create a small section. Air and water lines were ran through it to feed the root of each clone. A lot of twisting and poking of the root system had to be done but trauma should be minimal.

Once they recover, they’ll be pruned again and vegged for a couple more weeks or more.

September 6th

They are doing well and large enough to flower. Here are some individual shots of the flowers.

And here’s a group shot.

The DWC setup is currently running on GH nutrients with CalMag plus, Floralicious, Flora Blend, Rapid Start, and Hydroguard at pH 5.8 with PPM of 400. Nutrient temperature is stable at 65 to 67 degrees Fahrenheit.

They’ll start on their 12/12 light cycle soon. They’re big enough and mature enough. Estimated harvest date is November 17th.

September 9th

Here they are on their first day of flower. It seems they’re more than happy with the lighting change.

September 18th

Week one of flower in the books. Check out how green and happy they are.

September 22nd

One of the plants fell over. The roots just haven’t grow into the hydroton. Tried tying her up but she just wasn’t having it so out she goes! This grow is down to three cannabis plants.

September 25th

It’s been 2 weeks and 2 days since they were flipped to flower. They’re coming along nicely despite the pH on the low side for a few days. PPMs are quite low at 650 and temperatures are ok, running between 71 to 84 degrees Fahrenheit.

October 14th

Here they are at about 5 weeks. One of the plants showed some nutrient lockout from a low pH but it was corrected. All three had to be tied up because they were falling over. The passive air intake had to be rerouted and the temperature had to be lowered a bit. PPMs are also starting to decrease. Hopefully, the flowering process doesn’t go longer than 10 weeks.

October 28th

7 weeks in! The estimated flower time seems to be right on the money. These should be done in a couple more weeks – nice, short, flowering period. If you zoom in on the photos, you can see they’re nice and frosty.

Here’s to hoping they smoke as greatly as they look.

November 13th

On the 9th week, these plants were shifted to a 10/14 light cycle. They’ll get chopped pretty soon.

For those of you who missed it, this grow uses a “cool tube” 4000W with a 6-inch duct fan attached that blows air through the fixture and exhausts into the attic. It works pretty well with the passive intake routed to another room. This keeps daytime temperatures at the low 80s.

November 15th

Harvest day came 2 days earlier than expected! All the girls were chopped at 67 days of age just when they were starting to show amber trichomes.

December 2nd

This grow with three plants produced a total of 8 ounces of high quality weed even without a SCROG! This is an outstanding yield especially for a 400W light.

Grower: GreenMachine
Yield: 8 ounces
Location: NA

Except for a couple of minor snags along the way, this grow didn’t encounter a lot of problems. A problem-free without a lot of hassle is one of the advantages when using a DWC method in growing cannabis.

However, this grow journal was unable to elaborate on the advantages and other specifics of using DWC.

For example, people think DWC is harder than using soil as grow medium. This is far from the truth. Although it is true that every method has its own quirks one has to watch out for, the DWC can be easier than soil because it takes lesser time to manage.

DWC also necessitates the use of an air pump. Plant roots still need air and without an air pump, they will drown. Plant roots need oxygen, and the heavily oxygenated water contributes to the fast growth rate. Because of this, the air pump should never be turned off just for the purpose of saving electricity. Air pumps need to be running 24 hours a day.

And finally, the reservoir water used in this grow, and all other grows, are not required to be sterile to be effective.

Do you think you’re ready to start your first DWC grow?

Happy growing!

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