Hydroponics Marijuana Deep Water Culture (DWC) Guide, Part 3

In our first and second articles on maximizing hydroponics marijuana deep water culture growing, we got expert advice on nutrients, pH, oxygenation, water temperature and other important facets of DWC growing.

Marijuana growing expert Michael Straumietis, founder of hydroponics nutrients company Advanced Nutrients, is again sharing unique, professional techniques so you get faster growth, earlier-maturation, higher yields, and more potency from your DWC garden.

“One important fact most DWC growers have discovered is that you want to start your seeds in the smallest size rockwool cubes, or your cuttings in aeroponics cloners, to set your marijuana plants up for the bare root conditions of DWC,” Straumietis says.

Another advanced marijuana growing tactic specific to DWC is to manipulate water levels.

For example, during early grow phase, you keep your water levels high so that 80-95% of the root is covered, although you don’t want to actually submerge your marijuana plants’ stalks.

After your plants are firmly established in grow phase, you lower the water levels so 75-85% of the roots are covered in water.

Straumietis says high water levels in grow phase gives plants more leaf surface area and speeds up photosynthesis and growth rate, especially if you’re adding C02 to your marijuana grow room air.

“Then during bloom phase, you achieve two goals by lowering water levels so 60-75% of your roots are covered in nutrients water,” Straumietis says. “This creates more oxygenation for your roots, and also simulates ‘drought stress.’ Drought stress triggers your cannabis plants to produce more resins. Monitor your cannabis plants  during drought stress, so you avoid wilting your plants or overdrying roots.”

Manipulating DWC water levels is an art and a science, Straumietis explains, so be sure to do it carefully and incrementally so you don’t overdry your marijuana roots.

Another deep water culture problem Straumietis gets asked about is how to maintain the correct hydroponics nutrients concentration as marijuana plants use water and nutrients elements, and as water evaporates or is otherwise lost from the system.

If your water levels are too low, should you “top up” with zero ppm water, or with water containing hydroponics nutrients? If you put in nutrients water, what should your nutrients dosing be?

Straumietis says topping off deep water culture systems depends on what kind of nutrients you’re using, how well your marijuana plants are feeding, the visual condition of the nutrients water, and the water pH.

If your water is cloudy, smells bad, has pH way out of range, or has an EC or ppm that’s significantly higher or lower than what you started with, you should completely change out your water.

If your water is in good condition but your parts per million have changed more than 30%, you want to examine your cannabis plants to see if they show signs of overfeeding or underfeeding.

If you believe your marijuana plants are experiencing a nutrients deficit, check your pH and add water that has the same parts per million or slightly more dosing as your initial nutrients mix was.

For example, if you mixed a fresh reservoir at 500 ppm but after a week has dropped to 300 ppm, add 500-700 ppm water so you get back to 500 ppm.

If you believe your cannabis plants are being overfed and burned by excessive nutrients, top off your nutrients reservoir with pure reverse osmosis water or nutrients water that’s lower than your existing ppm. Your goal is to reduce your overall reservoir ppm so your cannabis plants aren’t being burned by excess nutrients salts.

You may have to do a few rounds of adding water to dilute or enrich your nutrients solution to get the ppm just right.

The process could take a few days, as you watch your marijuana plants to see the effects.

The nuances of adjusting water levels, topping up reservoirs and other factors are reasons that deep water culture marijuana growing works best for experienced growers familiar with plant health and how different marijuana strains respond to nutrients.

Straumietis explains that most brands of hydroponics nutrients aren’t manufactured properly as regards to pH stability and nutrients absorption.

“Because DWC depends solely on water to deliver nutrients and oxygen, defective nutrients and pH create more problems, more serious problems and more rapid onset of problems than if you’re growing in soil, soilless mix, coco, or rockwool,” Straumietis warns. “When you use Advanced Nutrients pH Perfect base nutrients and system supplements, everything is taken care of for you. In a properly tuned DWC system,  you mix your nutrients water using our bases and you won’t need to do a total change-out for about 10-16 days in most cases. Nor will  you need to worry about pH.”

Straumietis says water quality and water conditions are a key determining factor for DWC marijuana success.

“There are water-borne, root-destroying pathogens that could infest your marijuana roots. If you set your water temperature too high, you get pathogens and low oxygen. If you set your water temperature too low, you slow your plant metabolism and might damage the roots. And if you’re not using reverse osmosis water, you’re asking for problems,” Straumietis says.

Another tip Straumietis has for DWC marijuana growers is to use “growstones” instead of hydroton, rockwool, perlite, or other media in DWC net pots.

“Rockwool holds moisture and can rot your stalk or roots. Hydroton and other media are manufactured in harmful ways and don’t always work so well. Growstones are a newer, inert media, and their popularity is well-deserved,” he says.

As you can see from the videos embedded in our three-part deep water culture series, the advantages of deep water culture are obvious: supercharged, massive root systems, faster growth, faster-maturation, bigger buds, heavier harvests, more THC.

Straumietis advises you to provide the highest-quality, intense lighting to your marijuana plants grown in DWC, and also provide added C02, to take advantage of the metabolic and root benefits DWC gives your plants.

“Deep water culture is for dedicated cannabis growers who have the time, equipment, and knowledge to tune DWC properly,” Straumietis advises. “It’s worth it. When you have an optimized DWC system, you’re pushing your marijuana plants to maximum production capacity and you’ll see way more weight and THC than you get with most other hydroponics systems.”