There are many different systems that can be used to grow cannabis. Each of them has its own pros and cons. Yet, according to Bruce Granger, founder of Granger Consulting, there is one specifically that ensures a better yield and quality.
Dense growing medium
“If you look at a plant, the leaves breathe CO2 during the photosynthesis period, while during the non-photosynthesis period, it breathes oxygen,” Bruce explains. “On the other hand, the root system always breathes oxygen, it always needs it.”
Therefore, it is important to keep in mind that the root zone requires a constant oxygen input. But which growing system provides it with the most oxygen? “First of all, you can grow in dirt, which is the densest medium,” he explains. “Thus, it has a little amount of space to allow oxygen to get into. In a way, it really inhibits the ability of the roots to get oxygen. So, you could use peat moss or coco, which increases the space for the oxygen to circulate.”
Another growing system is rockwool. “This tends to be less dense and allows for more oxygen to get to the root system, but it is relatively confined, and operational cost can get a bit high for a number of reasons, such as more manpower needed and the necessity to dispose of the used rockwool.”
Hydroponics
Then, there is hydroponics. “In hydroponics, you are growing in water. But you can saturate the water with oxygen only so much.” To better understand the concept behind this, Bruce elaborates on an aspect. “Let’s look at the air. Oxygen exists in the air, 20% of our air is oxygen. Therefore, we are talking of a greater oxygen availability than in water. If the roots have access to all that oxygen, the result is that you maximize the speed the plant can grow. If growers enrich the rooms with CO2 to be given to leaves so they can grow faster, why not do something similar for the roots?”
Aeroponics does it better
And that’s how we get to aeroponics. “Aeroponics is a really effective and fast way to grow,” he remarks. “The real challenge with such a system, though, is twofold: you are dealing with sprayers and liners that spray the water which holds the nutrients to the root system; and on the other hand, how do you maintain a nutrient load consistent without keeping loading more water and nutrients?”
Aeroponics systems can be divided in two categories. “High pressure systems and low pressure systems. In high pressure systems, you are pushing water and nutrients through high pressure. The problem is that you are basically trying to aerosol the water, and this tends to clog the lines as you are trying to get the nutrients through that.”
“On the other hand, low pressure systems is what some people use in their gardens, and honestly, they hardly ever clog,” he points out. “There are a few companies that have aeroponic systems with a monitoring system. One of this is AEssenseGrows and their Aetrium products. They monitor the pressure in the lines, and there are sensors everywhere. In this way, you can also monitor the pressure and you get a warning when this increases or decreases. The pressure decreases because something got clogged on the supply side, e.g. there’s not enough water. Therefore, the solution to overcome the first challenge of aeroponics systems is using sensors.”
Monitoring is paramount
This is because, as Bruce explains, if one can properly monitor the system so that they know what is going on, they can reduce the probability of failure. “One of the things that I talk to my clients about a lot is: what is your grow methodology? Typically, they haven’t decided on that yet. Thus, I go through all the different methodologies: if you go dirt and rockwool, you have labor and disposable issues. The medium needs to be changed: when you go from cloning, to veg, to flower, you have to repot the plant in a bigger pot, which takes manpower, but also takes a new medium. Then, you end up throwing the old one away. Ultimately, cost and efficiency get directly affected.”
Bruce continues: “Aeroponics systems are probably three times more expensive on start-up than a conventional coco or dirt grow. But your labor cost goes down dramatically as there’s no repotting, as all you do is move the plant to a different piece of equipment. But the most interesting thing is when you look at water and nutrient cost.”
Indeed, Bruce points out how, in most other systems, the watering cost is really high because you allow water to drain out at the bottom, and that water is lost. “In a closed aeroponic system, the water is recycled constantly,” he says. “What the plant isn’t taking up, is just reintroduced to the plant, similarly to a closed hydroponic system.”
At the same time, saying that aeroponic growing would ensure increased yields is only part of the story, as the bigger picture tells a slightly different tale. “Ultimately, genetics of the plant is what determines the yield,” Bruce remarks. “There’s not much that a grow methodology can do on yield, as that’s really mainly based on genetics. Aeroponic systems would increase the speed at which the plant grows. And exactly because I can grow faster, I can go from having 5 cycles per year to 6 cycles per year. Thus, at the end of the year, aeroponic would increase the yield because you can get extra cycles. What “faster” really means is the efficiency of veg cycle and reduced turnaround times really are the keys to achieving the 6 cycles."
For more information:
Granger Consulting
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