Diving Into Water Culture
By Chris Bayley
With various levels of legalization being implemented across the nation, an increasing number of cultivators are practicing all-natural gardening techniques while taking advantage of temperate, sunshine-infused climates. This is mostly to due to working within the parameters Mother Nature has provided.
However, for many growers, these great conditions simply may not exist — hello, Alaska! For those growing indoors, water culture is an alternative to using soil that lands on the opposite end of the cultivation spectrum. Growers even have the choice to ditch mediums altogether if they want to. No medium? That’s right. Some hydroponic systems like the nutrient film technique (NFT) rely on a thin layer of water that travels through enclosed channels, whereby plants retrieve all the nutrient-rich solution they can tolerate.
If you’re an indoor grower, and knocking out heavy, consistent crops is your goal, then using a hydroponic system might just be what the doctor ordered. Controlled environments and hydroponics go hand-in-hand, and the combination gives growers the chance to really push the extremes that are possible when growing indoors.
Arjan Roskam, owner of the Greenhouse Seed Company and a great proponent of synthetic growing, once said “Grow big or go home,” and that’s exactly what this growing methodology is all about.
In this article, we’ll discuss why hydroponics and controlled-atmosphere growing environment (or C.A.G.E. for short) work so well together. We’ll look into the different parameters needed to fully optimize this growing technology, and then we’ll wrap things up by reviewing the most applicable hydroponic systems for unleashing your plant’s genetic potential.
Replacing Mother Nature
The thought of growing indoors and not in the ground may seem unusual, and a little counter-intuitive to some gardeners. Right out of the gate, the decision to grow indoors defies thousands of years of plant evolution, which have blueprinted plants to work within multiple symbiotic relationships that exist outdoors. The challenge that exists with growing indoors is to replicate Mother Nature using artificial lights and HVAC equipment, while simultaneously getting plants to thrive when clearly out of their element.
Lucky for us gardeners, plants, like humans, have different ways of utilizing nutrients. Outdoors in nature, plants utilize what’s called the soil food web (SFW) to receive their nutrients. When growing with synthetics, you bypass the SFW system and are essentially force-feeding plants. It’s akin to humans receiving nutrients intravenously as opposed to eating. The nutrients get there, just by a different means of delivery. It’s this different delivery system that hydroponic growing possible.
Pushing Botanical Extremes
A good analogy to explain the extremes that plants can be pushed to comparing a “natural” athlete to a performance enhanced athlete. We have all heard by now how prevalent the use of performance-enhancing drugs are in the professional sports world. Just as these artificial means allow athletes to reach new levels of performance, cannabis producers can use C.A.G.E., hydroponics and CO2 to “push” their plants well beyond standard growth rates. Growing “performance-enhanced plants” really has no downside in the short term. Like with humans though, these high-performance rates would likely take a toll on the plant’s physiological system if it were to endure these extremes over a sustained period of time. However, this should be of no concern, considering that most hydroponically-grown cannabis can go from clone to crop in under 12 weeks.
Consistent, heavy crops are a direct byproduct of combining beautiful growing conditions with a dialed-in fertilizer regimen. The goal should really be to grow your plants in what’s referred to as “pharmaceutical” type growing conditions. The fertilizer regimen includes the nutrient formulation, nutrient ratios and total dissolved solids, as well as the frequency and duration of feedings. Here’s one of the biggest secrets to achieving a high metabolic growth rate in plants (and it’s the same for humans) — don’t ever feed the plants more than they need. This concept seems simple, but unfortunately this idea gets largely overlooked in the synthetic growing community, where more is generally considered better. The goal should always be to use as little fertilizer as possible, or rather, learn to match the nutrient strength to the plant’s growth rate.
Hyper Growth Parameters
There are a multitude of factors to keep in mind when you begin pushing plants past their normal growth rates, and when doing so, it’s mandatory that all other parameters adjust accordingly. The old adage about the weakest link in the chain absolutely applies when obtaining this level of performance. Here is a breakdown of the parameters you’ll want to manipulate in order to facilitate faster than normal growth rates.
CO2
Our earth’s atmosphere currently has an ambient CO2 concentration of around 400 parts per million, which is up from around 250 parts per million before the Industrial Revolution went into full swing, starting in the mid- to late-1700s. Scientists have been experimenting with increased concentrations of CO2 to learn just how much plants can utilize. Through these experiments, it’s been observed that plants can handle upwards of a 500% increase in CO2 concentrations, which would be around 2,000 parts per million. Even though plants can handle those high concentration levels, a more ideal CO2 level for indoor cultivation is around 1,500 parts per million. Plants are more efficient at utilizing these increased levels of CO2 if the grow room temperatures are kept in the 80-85 degree range, which may prove favorably for growers having a hard time keeping their temperature in check. Keep in mind that if you’re relying on constant ventilation to keep your room cool, then adding CO2 will be a waste of time. CO2 is best used in rooms where the ambient air temperature can be kept in check via air conditioning systems that recirculate the air rather than removing it. Also, if you’re attempting to operate what is known as a closed-loop growing environment, then CO2 will be mandatory. These closed-loop systems rely on sensors to maintain a preset CO2 concentration level.
Heat
Along with in-room environmental regulation, the temperature of the water used in your hydroponic system may need to be augmented also. This is accomplished through a piece of equipment call a water chiller. These systems are closed-loop water recirculators that operate just like the radiator in your vehicle. As water recirculates from the growing system’s reservoir to the chilling unit, the nutrient water passes through coils where air is used to wick away the heat. There are industrial units capable of handling commercial size operations. If you are having a hard time regulating the ambient heat in your grow room, you will need a system like this to keep your plants happy and thriving. Plants can withstand higher temperatures in the growing rooms as long as the solution their roots are subjected to can be kept between 68 and 74 degrees.
Oxygen and Temperature Ideals for Nutrient Solutions
Aside from oxygen being one of the essential nutrients for plant survival, root systems live and thrive in an aerobic world. The amount of oxygen that can be contained within the nutrient solution and utilized by the plants is referred to as dissolved oxygen (DO). There is a direct correlation between temperature and DO levels. The higher the temperature rises in the nutrient solution, the less DO the solution can hold.
In order to fully saturate your nutrient solution, you’ll want to use an air pump along with air stones. Air stones break the incoming air stream into very small bubbles, which create a greater surface area, or point of contact, for the oxygen to dissolve into the nutrient solution. Creating a waterfall effect within the hydroponic system is another great way to keep the solution fully saturated. Full oxygen saturation is important for accelerated growth.
Deciding on the Right System
With so many ways to cultivate hydroponically, how does one go about deciding which method to use? To answer that question, let’s talk about the considerations to keep in mind when contemplating water culture systems. Then we’ll take a look at the systems that are available and how they operate.
User Friendly Systems
Hydroponic systems come in a variety styles. In the simplest terms, a basic hydroponic system can closely mimic growing in containers with soil, or can be as technical as a fog-infused aeroponic system. Whichever type of system you decide to go with, just remember, cleaning the system will be imperative between crops. The time involved for cleaning your system will be predicated on the complexity of the system. It’s highly recommended to follow the KISS philosophy here (keep it simply smart), especially until you’ve got a solid grasp of these growing methodologies’ idiosyncrasies.
Solution or Media Based Systems
Some hydroponic systems require a medium to be used; others can be operated without using a medium at all. The biggest difference between the two is the buffering capacity that using a medium will provide. Buffering capacity is defined by a medium’s ability to resist pH fluctuations throughout the growing cycle. Stabilizing the pH is critical for averting nutrient deficiencies and toxicities, which can happen through nutrient lock-out if the pH swings too far up or down. Growing mediums all have some degree of buffering action that can help stabilize the pH.
Solution-based growing systems have no medium to help buffer the nutrient solution’s pH and therefore must be monitored constantly.
Medium Culture
This type of system requires a medium that the plant’s roots will need to grow into. Simply fill your containers with a soilless mix or other inert medium which can then be hand watered. To automate this system, place the containers into flood and drain tables. Next, connect a reservoir to the table via poly hoses, and then attached to pumps, and voila, you just automated the system. This simple system can be scaled up as much as you’d like — no size is too large. This is a bottom-feed system that relies on the capillary action of the medium to move moisture up the container.
Stone wool works wonderful in this type of system. It’s an inexpensive way to grow hydroponically on a large scale, while producing great results. Top-feed systems, also known as drip systems, are just like the bottom-feed system, except it uses drip emitters that allow nutrient solution to enter the top and flow out the bottom. An advantage to a top-feed drip system is that the medium gets continuously flushed with every watering, taking away excess salts in the process.
Stone wool, perlite, vermiculite and expanded clay aggregate are some of the best substrates to use in medium culture. Commonly, these substrates are mixed to achieve differing levels of solution retention. There are many more substrates that could be used, but on a commercial scale, inert mediums are more suitable for decreasing possible pathogenic contamination. However, using biodegradable all-natural mediums have their upsides, such as being compostable, as opposed to taking up landfill space. These substrates include wood byproducts, coconut coir and rice hulls. A newer substrate some growers are experimenting with is sheep’s wool, which acts much in the same way as stone wool, but is completely renewable, like with the other natural sources. With different solution retention properties, some mediums will require one to two feedings a day, whereas others will require hourly feedings.
Solution Culture
Just as the name implies, these type of hydroponic systems require no medium at all. These systems operate by constantly submerging the plant’s roots in the nutrient solution, or are intermittently sprayed on timed cycles, or a hybrid system using both. The different systems that fall into this category are NFT, deep-water culture (DWC), aeroponics and fogponics. Unlike medium-based systems that offer some buffering, solution-based systems require the most attention. Depending on your experience level, it may behoove you to work your way up to these types of systems. The margin of error is smaller with solution-based systems and doesn’t take long for things to get out of control.
Hybrid Systems
Here is a solution-based hydroponic system that incorporates multiple system designs with outstanding results. This system integrates flood and drain tables with the operating efficiency of an NFT system. This system has been dubbed CRSPT, which stands for continuous-recirculation shallow pool technique. Most often the system is operated using four-foot by eight-foot flood and drain tables. Panda plastic or dark-colored Plexiglas sheets are used to sit atop the trays. Panda plastic can be cut to allow the placement of rock wool blocks, or your medium of choice, through to the tray below. If a medium-free version is desired, spaced holes in Plexiglas can receive neoprene pucks that are used to hold the plants in place. Once the plants are placed into the system, the pumps are turned on permanently and the water level is set to about a half inch. It is not uncommon to end up removing a one-inch deep mat of roots out of this system upon harvesting. This is an important point that should not be overlooked because a larger root system is directly correlated to a plant’s eventual size.
All-natural Hydroponics
The two most common terms describing the use of all-natural fertilizers in hydroponics is organoponics or bioponics. The attempted goal of this experiment is to replicate the quality potential of cannabis grown using an all-natural living soil mix. This method is perhaps the most difficult growing methodology in all of horticulture to master. Growers using this method are attempting to replicate the SFW within a liquid construct. There’s no place for stagnation in this system, and it’s absolutely fascinating. Get some time under your growing belt before taking this one on, but for seasoned growers, it is definitely a worthy challenge to experiment with. And if pulled off successfully, the results will be nothing short of spectacular.
Circling the Vortex
One great thing about hydroponics is that there are systems for any skill set. These systems can operate anywhere in the world. For example, NASA exclusively experiments with water culture as its choice for plant cultivation in space, which is one of the hurdles for interstellar exploration. Closer to home, hydroponics make it possible to grow food and cannabis in places that would normally be inhospitable to growing plants at all, such as our planet’s Polar regions.
Water culture is truly a beacon of hope for some. However, this article would be remiss if it didn’t address the main reason hydroponics gets a bad rap. Thousands of gallons of used nutrient solution gets dumped into our environment each year. Although this pollution pales in comparison to large-scale petro-chemical agriculture, it damages the environment all the same. If hydroponic systems are managed correctly, it’s possible to cut back on what exits your facility by 95%. There is no reason why cannabis growers shouldn’t take the lead in demonstrating earth-friendly agricultural practices. Hydroponics does have the capacity to be green. And isn’t being green what it’s all about anyway? Until next month, remember, stay focused and let it grow.
Chris Bayley operates Hortistructure, Inc. and Elemental Gardener out of Tonasket, Washington. He can be reached at 509-710-2820, or through hortistructure.net.