The idea of growing cannabis hydroponically isn’t nearly as frightening as it once was. When hydroponic growing was first unveiled to the general public, it was depicted as something used in large-format, commercial-size grows. Dutch botanists used it in their massive tulip greenhouses, and big names like Epcot and NASA were advertising the concept as the “way of the future” and a possible solution for growing food in space colonies with zero gravity. All of this made hydroponics sound like a daunting prospect for any would-be gardener, so it’s easy to see why cannabis growers didn’t take to it immediately—especially those growing at home.
Today, a lot has changed in terms of the perception and impact that hydroponics has had on cannabis growers. While hydroponic growing, by definition, simply means cultivating plants without soil, there are still many moving parts and technical aspects to consider. However, as hydro growing has moved into the mainstream, new advances in equipment, mediums and nutrients have made hydroponic systems the most widely used method of cannabis cultivation around the world. Here’s an overview of three of the easiest and most effective hydro systems on the market, as well as a glimpse of where hydroponics might be headed in the future.
Top-Feed Hydroponic Growing
Perhaps the most popular—and convenient—hydro system in use today is the top-feed setup. Utilizing either drip or spray emitters that are staked directly into the surface of the medium, these systems offer simple and reliable water and nutrient delivery to individual plant sites.
Top-feed systems are usually drain-to-waste, but they can also be used as a recirculating system. Most often, these systems use flood tables to hold the plant containers and catch the runoff from each plant site. This runoff can be collected and either directed back to the main reservoir or siphoned out to a drain.
Plant sites within the flood table can use various types of grow medium. Advanced growers knowledgeable in nutrient-dosing programs might prefer to use rockwool slabs or large 8-inch cubes to hold their plants, while beginners may choose fabric pots with a soilless peat- or coco-based medium, which is much more forgiving when it comes to mistakes with fertilizers.
The primary concern in these systems is clogging the thin spaghetti tubes that feed the emitters, as well as clogging the emitters themselves. Some new growers may be turned off by this “moving parts” aspect, as these systems do require larger reservoirs, pumps and timers—but overall, top-feed systems offer flexibility, scalability and customization for all growers, whether you’re a beginner or someone with years of experience.
One of the first hydroponic systems to hit the market, flood-and-drain (also known as ebb-and-flow) tables are simple to set up and easy to use. The system involves using flood tables to house the porous containers so that when the table is flooded, the medium holding the plants’ roots becomes saturated with water and nutrients.
Flood-and-drain systems commonly use “netted” containers (Gro Pro, Current Culture, etc.) or Smart Pots to hold the individual plants. These plastic pots have wide openings or slits around the sides and bottom to allow the water and nutrient solution to completely flood the interior of the pots. This allows the medium to soak up and retain large amounts of moisture.
Depending on the medium and nutrient program being used, flood-and-drain systems can be drain-to-waste or can recirculate the water. For home growers, the latter can be achieved simply by housing the system reservoir directly beneath the flood table. In this case, the water is usually only recirculated for a one- or two-day period (perhaps more if only purified water and no nutrients are used) before the reservoir is emptied and refilled with fresh water.
Deep-water culture (DWC) systems represent an all-in-one turnkey solution for hydroponic growers and offer good scalability for both small and medium-size growrooms. DWC systems use large (usually 5-gallon) buckets to hold the individual plants, which rest in a netted pot nestled into a hole in the bucket’s lid. The buckets are daisy-chained together by water lines at the base of each. A reservoir-and-pump system fills each plant site with water, which rises from the bottom to the top of each site. The roots hang down into the buckets and suck up water and nutrients.
One great aspect of DWC systems is that the pump timer can be set to fill and drain the buckets on any schedule, meaning that roots can sit in water for several minutes at a time, several times a day. When no water is present in the buckets, the roots are efficiently aerated. This is especially beneficial during the dark cycle, when the above-surface plant is “asleep” and the roots are working, growing and breathing in oxygen (remember, roots breathe in O2 while the rest of the plant breathes in CO2).
DWC systems are known to grow large root systems, resulting in massive plants. As a result, these systems deliver some of the largest yields of any hydro setup. Single-reservoir DWC systems range from two to 12 plants sites; however, they can get much larger if additional reservoir-and-pump systems are added. Because this is relatively easy to do, DWC growers can scale these systems up to commercial-size operations, garnering huge yields with each cycle. Home growers can max out their yields as well by using smart trelliswork around the plant sites in conjunction with good topping techniques. With the dissemination of more and more reliable cultivation information on the subject, DWC systems are on the rise and may soon be the home grower’s top choice.
Hydro Nutrient Programs
Perhaps the most difficult aspect of hydroponic gardening is the implementation of an effective nutrient program. When dealing with water culture, the old adage of “Less is more” certainly holds true. For beginners, it is definitely important to remember that you can always increase the dosage, but it’s extremely difficult to remedy overfeeding.
As an example, studies have shown that gardens using nutrient solutions with high parts-per-million (ppm) levels of dissolved solids were consuming less water on a daily basis. When the ppm was lowered, the plants drank much more. The reason is that the high ppm levels created by overfertilizing caused higher osmotic pressure at the molecular level. Essentially, the plants were unable to absorb moisture due to the higher presence of dissolved minerals. The result was a big decline in both yields and potency.
For this reason, many hydro growers chose to use milder, liquid-based nutrients; more often than not, organic (or even veganic) nutrient solutions provide the best results. Also, synthetic nutrients are mostly salt-based. This not only increases ppm levels, but synthetic nutrients also don’t dissolve as easily and tend to clog irrigation lines and drip emitters.
There are currently many excellent brands offering organic nutrients created just for hydroponics. General Hydroponics, Advanced Nutrients, Botanicare and Pure Life Veganix all have excellent lines for hydro growing. Remember, when creating nutrient programs for your system, it is essential to have a pH and EC (electrical conductivity) meter on hand to help you evaluate doses and ratios. You should never rely solely on the manufacturer’s instructions, as these tend to go above and beyond what the plants actually need. As a rule of thumb, keep your nutrient solution at a pH of 6.0 and the EC between 2.0 and 3.0.
Hybrid Hydro: The Future of Hydroponics
With an eye toward the future, many advanced growers are now customizing their hydro systems to accommodate their space, strain and yield requirements. Given that the objective of hydroponics is to provide adequate moisture so that minerals dissolved in the water can be easily absorbed by the roots, the opportunity for new ideas and approaches is clear. In the past, these have led to the advent of new or improved hydro systems, which now number in the dozens. Recently, we found such a system in use at the Breakwater Alternative Health Center in Cranbury, New Jersey.
Top Feed + NFT
Nutrient-film technique, or NFT, is another type of hydroponic cultivation in wide use today by large-format, commercial-size grow ops. In this setup, plants are suspended in the medium with their roots hanging down, much like a DWC system. However, instead of being contained in a flood bucket, the roots dangle into a trough that sits at a very slight angle so that the water poured into it will collect and drain at one end. This trough provides a thick, constant flow of water—or nutrient film—that the roots soak up as needed. As an added bonus, due to the exposed nature of the trough, the root zone lives in the open air, giving the roots access to enormous amounts of oxygen.
At Breakwater, the troughs in the flowering rooms are engineered to continuously flow with the nutrient solution (dissolved nutrients in filtered water) via a top-feed irrigation system. The benefits here are twofold. First, the bulk of the plants’ roots sit in a firm medium (HEC in this case) that supports them while also retaining some moisture. Second, rather than drain-to-waste, the nutrient solution collects in the trough that runs beneath all of the plants in a row, allowing the dangling roots that have grown out of the containers to sap up additional nutrient solution as needed. At the end of the trough, the water is collected and redirected to the main reservoirs for a continual (nonstop) flow back through the gardens.
The larger yields associated with hydroponic growing are directly correlated with faster growth.
“The biggest advantage to hydroponics is the growth rate of the plants,” confirms Joe Bender, chief horticulturalist at Breakwater Alternative Health Center. “A constantly recirculating nutrient solution ensures that the roots are always bathed in a steady supply of nutrients, while still constantly providing plenty of oxygen for the roots.”
Since roots need oxygen for respiration, Bender explains, a potting mix won’t hold the optimal amount of oxygen to sustain the accelerated growth that hydroponics creates. “A freshly watered potting mix, such as peat, perlite and vermiculite in a 3:1:1 ratio, holds less oxygen than is ideal for roots. Therefore, plants grown in potting mix must dry between waterings in order to provide sufficient oxygen to the roots,” he observes. “As a potting mix dries, it gradually allows more oxygen to reach the roots, but simultaneously water and dissolved nutrients become harder for the roots to absorb, and the solution in the area surrounding the roots becomes depleted of nutrients—unlike in a hydroponic system, which constantly replenishes this would-be depletion zone. The combination of constantly available, optimal levels of both water and oxygen in a hydroponic system allows plants to grow much faster.”
Breakwater avoids oxygenating the reservoirs with air pumps, because the growers don’t want to force microbes from the air into the solution—not to mention that keeping the nutrient solution cool (the reservoirs are maintained at 66.5°F) allows it to hold the maximum possible amount of dissolved oxygen. Furthermore, the nutrients pouring from the drippers and through the pebbles in the pots, then pouring from the troughs into the collection gutters along the wall, then circulating from the gutters to the return reservoir, and finally getting pumped and dumped back into the main tank—all at a very high rate of flow—allows enormous amounts of oxygen to efficiently dissolve into the water. And this process is constant, 24 hours a day.
However, one drawback with any hydroponic system—especially one that runs nonstop—is algae, which clogs the drippers, is difficult to clean post-harvest, and decreases the oxygen content of the nutrient solution. Algae’s effect on the dissolved-oxygen concentration in the Breakwater system hasn’t been causing any problems (i.e., no root rot, with healthy-looking roots and plants), but steps have recently been taken to keep light from reaching the nutrient solution. Since algae can be expected to be a nuisance in any hydroponic system, growers should design their setups to minimize the nutrient solution’s exposure to light as much as possible.
Reaping the Rewards
With 480 plants per flowering room, the hybrid hydro system at Breakwater helps ensure that the plants always have enough water and nutrients on demand. With a vegetative cycle of just two weeks and a flowering cycle that ranges from seven and a half weeks (60 days) to 11 weeks, depending on the strain, the average yield here is around 125 pounds per flowering room, with maximum yields climbing as high as 186 pounds per room. With 88 lights per room, this system produces over 2 pounds per 1,000-watt lamp.
The max yields are achieved when Breakwater grows its best-yielding strains, notably AK-47 and Bubblegum, both propagated from seed from the Dutch breeders at Serious Seeds. Other popular strains among the patients at Breakwater include Dutch Passion’s Orange Bud (an inbred Skunk selection), an incredibly rare pheno of the Lemon G, and the highly medicinal Cannatonic, which has a 1:1 ratio of CBD and THC. The combination of high-quality genetics with an ingenious, commercial-size hydroponic facility means that these New Jersey flowers will hold their own against those of any other dispensary nationwide.
“So when will there be a Medical Cannabis Cup in New Jersey?” Bender asks.
Who can say? But regardless of when that happens, 2017 is looking like a ripe year for the East Coast.
Related: The History of Hydroponics
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