Another year flashes by and we arrive back to the annual “High Times Hydro Report”—a place of learning for those interested in growing crops of buds without soil and for those already eyeball deep into cannabis water culture.
Why Grow in Water?
Say what? Of course plants need water. Yes, but they don’t need soil! In hydroponics, an inert growing medium—if any is used at all—replaces the soil. All of the necessary elements or nutrients that a cannabis plant uses to complete its life cycle are supplied in a nutrient solution.
The word “hydroponics” is from ancient Greece, and it literally translates to “growing with water,” or, in this case, with a nutrient solution.
There are plenty of advantages to growing with water. Here are just a few.
Increased Oxygen Levels for Roots
Cannabis roots love oxygen, and the more they can get via dissolved oxygen (DO) and ambient levels, the faster and bigger the plants will grow. Modern growers are just beginning to unlock the potential of increased O2 levels and are making some amazing discoveries. For example, crops can grow bigger with less fertilizer when they have higher O2 levels at the roots.
Furthermore, the aerial portion (the upper green parts) of the crop can still grow and thrive in less-than-perfect conditions (e.g., high humidity in a greenhouse) when there is more O2 for the roots.
Note that a nutrient solution can hold considerably more oxygen than soil or a grow substrate, which makes growing with a water a natural choice for amping up O2 to supercharge crops of heavy and healthy buds—naturally!
Thermodynamics for Efficiency
Water, the main component of a hydroponic nutrient solution, is a much better conductor for heating and cooling than air. That’s why most combustion engines are liquid-cooled instead of air-cooled—fluids do a better job of trapping and transferring temperature differences between the engine and the air.
It is far less efficient to cool or heat the air in an environment like a greenhouse or growroom than it is to cool or heat a nutrient solution. In reality, the plants don’t care what the air temperature is; they care what their core temperature is—the leaf temperature.
Think of sinking your feet into a cool stream on a hot summer day—or placing a cold cloth on your forehead if you are feverish. This does a great job of cooling your whole body by lowering your core temperature. It’s the same thing for cannabis plants: If you cool or heat the nutrient solution that the roots are immersed in, you effectively raise or lower the temperature of the whole plant. This keeps photosynthesis humming along when it may otherwise slow or halt due to warm or cold air temperatures.
Eliminate or Lower Replacement Costs Between Crops
Lugging out old root-balls of dirt or medium from previous crops is messy and costly, to say the least. Furthermore, there are costs associated with disposal and replacement—and these will occur every time you want to replant. With hydroponic methods like NFT, DWC/RDWC, aeroponics, etc. (see “The ABCs of Cannabis Hydroponics Systems” below), there is essentially little to no growing medium to replace; the plants only require mechanical support, as the roots are actually growing in the nutrient solution. This means that a five-foot-round bush might only need as much growing medium, like grow rocks, as would fit in a large-size soda-fountain cup. Compare that to a 20-gallon nursery pot then multiply by the number of plants and you may quickly realize the benefits here. Besides the cost of materials, this means a fast crop turnaround between harvest and planting. The system can be drained, scrubbed and replanted within hours instead of the days required by traditional methods, with very little if anything at all to haul away and dispose of.
Hydroponic System Basics: Recirculating vs. Drain-to-Waste
These are the two basic classifications of hydroponic systems. A recirculating system can also be referred to as an active system. Here, the nutrient solution is reused, circulating through cannabis-plant roots via an active water pump or air pump.
When water falls or moves through the air, it absorbs oxygen. A further benefit of recirculating systems is that they conserve water and fertilizer, reducing the environmental footprint of any cannabis garden. Note a well-sealed (covered) recirculating hydroponic system uses around 50 percent less water than is used in conventional soil growing and irrigation methods (watch dirt growers squirm a bit when you talk about water use).
Drain-to-waste hydroponic systems may still use a water or air pump to distribute the nutrient solution; however, the main difference here is that the solution is not recaptured back into a reservoir after reaching the plant roots and then reused. After each irrigation cycle, the nutrient solution is collected as waste. Thoughtful growers will find other uses for spent nutrient solution, such as irrigating orchards where trees or shrubs are happy to drink up the extra water and nutrients.
The ABCs of Cannabis Hydroponics Systems
In an aeroponic system (the method was pioneered in Israel for performance and water conservation by Dr. Hillel Soffer), plant roots are sealed underneath a light-tight lid, with the upper part of the plant exposed to light. The bare plant roots are intermittently or continuously sprayed with a nutrient-solution mist.
One of the advantages of aeroponics is a very fast growth rate due to the large surface area generated by misting roots, which spurs oxygen absorption. A drawback is that misters are subject to clogging without lots of care and attention.
There are countless variations on the drip-system setup. Essentially, individual plants are irrigated via top feeding of nutrient solution at the base of each plant with “spaghetti” tubing, usually around a quarter-inch diameter. The spaghetti tubing is typically connected to a wider-diameter tube that is supplied by a pump from a reservoir or injector system with gate valves. These systems can be operated as recirculating or drain-to-waste. A bucket system is a type of drip system, as are drip trays (or modified flood tables—see below).
The advantages of the drip system include very precise moisture management with timers or sensors. This system can also easily be scaled up or down depending on how many plants you may have in the garden area at any given time. Clogged emitters or lines are a disadvantage, as are the routine inspections required to make sure they are flowing freely to the thirsty cannabis plants they are supplying.
Deep-Water Culture (DWC)
This is perhaps the first modern hydroponic growing method, and it’s still widely used today. When using this method, a plant is supported by a collar or net pot in a light-tight container, like a black bucket or tote with a sturdy lid. A depth of nutrient solution is maintained just below the bottom of the net cup or stem supported by the collar. The nutrient solution is aerated or “bubbled” by an air pump (aquarium air pumps and stones are often used).
DWC has the advantage of being very inexpensive and easy to set up. Its drawback is that the air stones or bubblers don’t draw much oxygen into the system.
Flood & Drain (or Ebb & Flo)
In this system, shallow water-tight trays with grooves in the bottom leading to a drain/fill hose connection holds grow cubes, slabs or pots (sometimes trays are simply filled with medium). Beneath the supported flood table is a reservoir containing nutrient solution with a pump and timer connected to the fill/drain hose. Periodically, the pump fills the tray with a shallow depth of nutrient solution, fertigating the cannabis crop. When the pump shuts off, the solution drains back through the hose and into the reservoir, drawing fresh air into the growing medium for the roots.
The main advantage with this system is that it can be forgiving with power outages, inexperienced hydro-system management and other missteps. There are very few moving parts here for an active system. Its main disadvantage is that larger amounts of inert growing medium are usually required for its operation than in other systems.
Nutrient Film/Flow Technique (NFT)
Pioneered in the United Kingdom, NFT is a well-proven and widely adapted system favored by commercial veggie and fruit growers all over the world. The basic concept utilizes shallow troughs or channels with lids (or as one-piece tubes) that have holes drilled or punched on top, usually at a fairly close spacing, arranged on a gentle slope. At the high end of the trough, a nutrient-solution emitter (such as spaghetti tubing) delivers a continuous flow of nutrient solution.
The solution flows as a shallow film down the length of the channel across plant roots, drawing air into the solution. The plants are placed into the channel through the holes on the top of the tube or lid. At the lower end, the solution is captured and redirected back to a reservoir, where it is pumped back to the high end of the system for continuous recirculation via emitters.
This method’s advantage is that a large-scale system can be set up easily and quickly, as there are few parts to contend with. Furthermore, the system can be very productive, and it’s well suited for mechanization.
Some might find the higher planting density (which is best for shorter plants) to be a disadvantage, and if there is a power outage there won’t be much nutrient solution in the root zone to keep plants sustained for significant periods of time.
Recirculating Deep-Water Culture (RDWC)
A modernized and amped version of the DWC system, RDWC takes advantage of all the proven principles of DWC and adds the otherwise missing recirculation component. While that’s an oversimplified way of putting it, recirculating the solution greatly improves crop performance and the practical layout potential of the system, making it highly suited to commercial-scale cannabis growing. The amount of dissolved oxygen (DO) that can be achieved in a RDWC setup is very tough to beat. Oftentimes, growers are able to run their RDWC systems with quarter-strength nutrients while still growing huge and lush cannabis plants compared with conventional nutrient-solution concentrations due to the superior DO levels achieved.
Important Terms & Principles in Hydroponics
Dissolved oxygen refers to the level of oxygen that has been dissolved into the nutrient solution that is available to plant roots. Cannabis plants thrive in aerobic (oxygen-rich) conditions. Anaerobic conditions, those lacking oxygen, can be detrimental and promote poor nutrient absorption and increase the potential for root rot.
Electrical conductivity, which also is the base value for readings like total dissolved solids (TDS, measured in parts per million, or PPM), refers to the fertility load or potential that is measured within the nutrient solution. For example, the more soluble fertilizer you add to the solution, the higher the value becomes.
pH is a measurement that refers to the relative acidity or alkalinity of substance, in this case a hydroponic nutrient solution. Different nutrients are more available at different pH levels, so it’s important than an optimal range, or “sweet spot,” is maintained. Usually a pH of 5.8 to 6.2 is good for most hydroponic garden types.
To get an idea of where hydroponic technology is heading and what it means for growing cannabis in the days to come, we caught up with some of the leading minds involved in the field.
Christian Long, co-founder and co-developer of Current Culture H2O (cch2o.com) Under Current systems and related technologies, had a few new tools to share that are now available to growers as well as some insights into what the future of growing buds with water culture may hold.
For the everyday hydroponic grower using recirculating reservoirs or applying aeration to systems via air pumps, CCH2O’s new AirReg and Add Back Kit are very useful tools in getting the most out of your hydro system.
The AirReg Kit allows growers to create a measurable amount of aeration through their systems with a bleeder, valve and gauge (measured in inches of water). What’s significant here is that anything over 25 on the dial means that you could actually be oxidizing nutrients—too little and you may not be getting all the air to your cannabis roots that they can use. The Add Back Kit uses a venturi injector that works with any water pump rated at over 500 gallons per hour. Instead of dumping pH adjusters or nutrient concentrates into the system, which can shock plants, the kit provides an attachment to your system pump that siphons up concentrates and adds them to the system at a steady and gradual rate that you control. It’s very handy and does not require any additional power.
Long was very excited to talk about CCH2O’s automatic dosing system. The new doser can be preprogrammed to grow perfect cannabis crops, using ratios and values the company has researched and developed over many years with the help of growers from around the world. The programming adds the right amount of each component in the Cultured Solutions feeding program at the right times. No more guessing what’s optimal or trying to remember how much of what part you added the time before—this keeps your hydro system dialed in 24/7 to optimal pH, EC and ORP (oxidation reduction potential) levels.
SOPs (standard operating procedures) are a big deal with the new generation of legally sanctioned cannabis mega-producers; they are essentially the “playbooks” for their grows. Some of the trends that are emerging and undergoing further development from industry leaders like CCH2O and EZ-Clone incorporate SOPs into technologies like controllers used to run these cannabis mega-farms.
Here’s some of what Billy Blackburn, CEO of EZ- Clone who recently joined forces with GrowLife Inc. and is also now heading GrowLife product development, had to say on the subject:
“While SOPs are invaluable to professional growers, there still needs to be a level of thinking and intelligence making the day-to-day or even moment-to-moment decisions that affect the growing environment.
“For example, when growing on a large scale, consistency is really important—something we know very well in developing aeroponic systems that automate and speed up the cloning process. That’s why we are working with experts in their respective fields in developing controls and sensors for grows that allow us to give them a level of thinking or intelligence—AI [artificial intelligence], more specifically.
“Taking years’ worth of data based on real cannabis growing and incorporating that into how a controller behaves or makes decisions in a complex growing environment is now emerging over the horizon and we are really excited to be a part of that—empowering cannabis growers of every scale to produce the best crops possible while freeing up some of their time and lessening the worry or risk in their endeavors.”
As part of the SOP growing trend, EZ Clone’s Commercial Pro System can be supplied with a comprehensive SOP guide to cloning and mother plants—we are talking about stuff far beyond the basic and rudimentary here. For example, how to avoid creating genetic drift in your valued genetics that may occur over time with successive cloning, and what percentage of a mother plant is acceptable to cut for cloning and how often. The SOP guide will help you quickly understand and utilize information that took many years of hands-on experience and feedback from countless cannabis propagators to develop.
While hydroponics is not a new technology, there are exciting and new technologies from other fields that are crossing the stream and finding their way into growing hydroponic crops of buds—better, stronger, faster!
This article was originally published in the February 2019 issue. Click here to get a subscription!