How To Implement Enhanced CO2 Into Your Grow Space
A Partnered Article with Alex Neil at Dr.Cannabis.Io.
Every cannabis grower's dream is to harvest big, sticky buds. To increase plant yield, indoor growers pay attention to the big 3: water, nutrients and light.
However, modern growers know adding carbon dioxide to the grow space can take yields from good to great.
What is CO2 Anyway?
Carbon dioxide gas is necessary to support life. People breath in oxygen and exhale CO2. Plants take in CO2 and put out oxygen. This without this oxygen and carbon dioxide cycle there would be no life on earth as we know it.
However, carbon dioxide has gotten a bad rap. When most people think of CO2, they think of global warming or in the extreme case CO2 poisoning. While CO2 concentrations greater than 3% are dangerous to human health, that level is almost never found in nature, and is much more than the amount cannabis plants need to grow.
To put it in perspective, CO2 makes up about 0.04% or 400 ppm of the earth’s atmosphere. Double that in an enclosed greenhouse and you'll get sleepy, but your plants will thrive.
Why do Cannabis Plants Need CO2?
Like all other green plants, cannabis transforms light energy into chemical energy through a process called photosynthesis. Chlorophyll-containing organelles known as chloroplasts convert CO2, water, and minerals into organic compounds that are rich in chemical energy plants use to grow.
Fortunately for us, oxygen is a by-product of the process. It is released by the plants during the day as they absorb CO2. The gases are released and absorbed via the plants’ stomata, which are minute openings surrounded by guard cells on the undersides of their leaves.
If a cannabis plant does not get enough CO2 they will continue to grow until their stored sugars are depleted. Once that happens, their metabolism decreases, and they show little to no signs of growth.
On the other hand, if a plant gets too much CO2 it will slow down or even stop photosynthesis. The trick is finding the right gas level for a grow space to speed up photosynthesis and lead to abundant growth and boosted yields.
How Much CO2 Is Enough?
The optimal amount of CO2 required to boost the yield of cannabis plants depends on several factors including the intensity of the light and the size of the grow space. In an indoor space with normal ventilation, the concentrations of CO2 should be around 400ppm, which leads to growth rates like what you would expect if you were growing your plants outdoors.
Growers have achieved the best success with CO2 levels between 1,200ppm and 1,500ppm. However, you cannot simply increase the CO2 level unless your plants can use it.
CO2 and Light
If you are growing your cannabis plants under low light (around 12,330 lux/1150 fc), you can increase their photosynthesis by maintaining CO2 levels at 400ppm. For additional growth you will need to increase the intensity of your grow lights.
Increasing the light intensity to somewhere around 49,310 lux/4600 fc allows you to increase the CO2 level and therefore, plant growth. The rate of photosynthesis will speed up as you raise the CO2 level to 600ppm. Beyond that, the rate will increase more slowly. You can increase the level to as much as 1200ppm under that lighting, although photosynthesis will be even slower.
If you can increase the light intensity to 59,201 lux/5500 fc, your cannabis plants can use increased CO2 levels of between 1200 and 1300ppm. You could increase the level to 1500 ppm if your light intensity increases to 80,400 lux/7500 fc. Growers who have taken it to that level recorded a 100% increase in their plants’ growth rate.
Calculating the Amount of CO2 Required
As tempting as it may be to rush out, purchase a tank of CO2 and empty it into your cannabis grow space, that would probably be the worst thing you could do for yourself and your plants. First, you should always use a simple calculation to work out how much CO2 your space needs.
Let's say you want to increase the level of the gas to 1,000ppm. To work out how much you need, multiply the room’s cubic area (length x width x height) by 0.001. The result is the number of square meters of CO2 you need.
For example, a room that is 4m long, 4m wide, and 3m high has a cubic area of 48 cubic meters (4 x 4 x 3 = 48). Multiply 48 by 0.001, and the result is 0.048 cubic meters. In other words, it only takes this small volume of CO2 to raise the level to 1,000ppm.
Increase CO2 Levels the Easy Way
There are various ways in which you can increase the CO2 level in your cannabis grow space. You can do it the impractical way by asking a few friends to join you in sitting in the grow room and breathing deeply, or by buying a large chunk of dry ice and letting it do its thing. Another way would be to use a generator that uses natural gas or propane to produce CO2.
The easier, more effective alternative is to purchase professional measuring equipment and to install a set-up that will supply the right amount of CO2. The basic equipment you need is a meter such as the Carbon Dioxide Handheld Gas Detector or a Day Night CO2 Monitor & Controller for Greenhouses, a CO2 tank regulator with solenoid valve, and a tank of CO2.
Assuming you get the basics, you would measure the amount of CO2 in the atmosphere, release CO2 from the tank using the regulator and valve, and then take another measurement. If you have the funds, you can purchase the equipment for a more elaborate set-up that can streamline the process, and that can help make it safer for you and your cannabis plants.
Using CO2 safely and correctly in your grow space may be the final step you need to take for a healthy crop. If you are not achieving the right levels of CO2, you may well be missing out on the best possible yield.
See DrCannabis.Io for more tips and guides on plant growth.