Despite all the various styles, setups and secrets used to grow cannabis, one of the primary choices for growers revolves around whether or not to use soil.
While soil can be a more forgiving medium, many growers and some cannabis aficionados swear that hydroponically grown marijuana has a cleaner taste than its dirt-grown counterparts. However, others argue that soil and organic-based growing methods produce a more flavorful final product.
“Hydroponics is not a magic wand to fix poor growing habits and bad genetics,” says Dan Lubkeman, president of the Hydroponic Society of America. “There is no magic wand.”
When done properly, hydroponics can produce bigger, stronger plants with larger overall yields and more control over temperature, nutrients and pH levels, compared to more traditional growing mediums, according to Current Culture H2O vice president Christian Long.
So for those looking to ditch the dirt, Marijuana Venture spoke with a few experts to find out what they consider to be the most important factors to consider when setting up a hydroponic growing system, whether it’s for tomatoes or cannabis.
CHOOSE THE RIGHT SYSTEM
While many people think hydroponic cultivation requires a purely water-based medium, it really means “growing without soil.”
There are a handful of styles of hydroponic growing, from a drip method that drizzles nutrients through the growing medium to a “flood and drain” method in which the growing media is periodically flooded, rather than keeping the roots fully submerged. There’s also the aeroponic method, which uses mini-sprayers and sprinklers to mist the roots, and the nutrient film technique (NFT), which sets the roots in a thin film of nutrient solution to expose more of the root to oxygen.
Long has been with Current Culture since it launched in 2006. Prior to helping start the California-based company, he worked in hydroponic retail for a handful of years and says he has plenty of experience as a hydro grower himself.
While the NFT method is popular for small crops like lettuce and other leafy greens, Long says it’s not particularly useful for growing commercial quantities of cannabis.
For most cannabis growers, Long recommends what is known as a “deep water culture,” in which the roots of a plant are completely submerged in nutrient-rich water.
Keeping your hydroponic room clean is key to producing top quality hydroponic cannabis and repeating the results. Photo courtesy of Current Culture H20.
TEMP CONTROL
Long’s first piece of advice is to get a water chiller to ensure that water temperature stays between 65 and 68 degrees Fahrenheit. The temperature not only helps keep away pests and pathogens, but will help maintain dissolved oxygen levels in the nutrient solution.
“Every degree that water temperature goes up from 68, its ability to hold on to that oxygen diminishes,” Long says, adding that colder water will also help create a heat sink to pull unwanted heat away from lights and other equipment.
WATER LEVELS
Maintaining the proper water level through growth and bloom is another important factor growers to pay attention to. The water level should stay fairly high, according to Long, in order to ensure the plants stay hydrated. However, if the water level gets too high, the plant can get “water-logged.” Long suggests keeping the water right at the tip of the root crown, but below where the stalk of the plant begins.
As the roots develop and the plant gets closer to blooming, Long says water levels can be lowered to expose more root mass. He believes creating drought-like conditions in late bloom can aid bud formation.
To keep water levels where they’re needed, Long recommends having a top-off reservoir connected to a float valve to help maintain consistent water levels. Water and nutrients can be added to the reservoir when needed instead of directly into the system itself as plants use up the solution.
“As plants are feeding, you’re going to see a drop,” Long says.
Deep water culture systems, like those made by Current Culture H2O, provide a better butrient base for cannabis than the nutrient film technique used for leafy greens like lettuce. Photo courtesy of Current Culture H2O.
MAINTAIN THE pH
Long recommends a pH between 5.5 and 6.5 in a deep water system, which allows for more leeway than a dirt or drip system, he says.
However, he adds that any adjustments to pH or other nutrients in the water solution should be diluted and added through the top-off reservoir to prevent any concentrated pH adjusters from resulting in plant/root shock.
WATCH THOSE NUTRIENTS
While it’s important to make sure the plants are getting everything they need to grow, Long says the nutrients needed by cannabis are more similar than dissimilar to those needed by any other plant. He suggests a “really clean and simple” formula. For example, Long says the nutrient blends sold by his company are mineral salts dissolved in water, with no bacteria or organics added.
Keeping the focus on water and pure mineral salts will get the most efficiency out of your nutrients and keep the nutrient solution viable for longer, he says.
Although a deep water culture system can run with only top-offs to the reservoir system, Long still recommends a full nutrient change-out every 14-21 days, timed with the various cycles of the plant to help give a boost to the next stage.
“Anytime you put fresh solution in there, the plants like that,” Long says.
Growers using more complex nutrient solutions with heavy organic inputs should change the solution more frequently, every 7-10 days.
KEEP IT CLEAN
Finally, making sure the system is fully cleaned between grow cycles ensures that each crop gets a fresh start, free of any buildup and biofilms that may be present from the previous cycle.
Long suggests a water conditioner that is a weak acid to help remove mineral salts. Cycle it through the system for 24 hours and then thoroughly rinse and allow all equipment to dry before beginning the next growth cycle.
But it’s important that the entire environment remains clean, not just the water solution. Long preaches simplicity in setup, with few obstructions and as clean a room as possible. Lubkeman agrees, adding that even plant debris or pathogens brought into the room on an unclean shoe can affect a grow.
TAKE GOOD NOTES
Even when sticking with best practices for growing, Lubkeman says the key to success in hydroponics is to “keep good notes and to keep it clean.”
“I meet so few people who take notes,” he says, adding that being consistent is the key to repeatable results. “Be scientific.”
Lubkeman recommends keeping records of temperatures, nutrient dosage rates, frequency of application, pH data and, of course, nutrient data.
“Over-fertilization and under-fertilization are the two most common killers in the garden,” he says.
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