Once you’ve mastered the basics of growing cannabis, you can explore more advanced growing methods. Things like light, temperature, and humidity are incredibly important. However, there are other factors that affect how your cannabis grows, like CO2. In fact, there are several ways to use CO2 to increase cannabis yields.
You probably remember from science class that plants need CO2 to live. Every plant on the planet uses CO2 similarly to how humans use oxygen. Essentially, plants “breathe in” CO2 through their leaves, and “exhale out” O2, or oxygen gas.
Unlike the animal process of breathing, plants only use CO2 when it’s light out. The CO2 they use is part of the process of photosynthesis. The more CO2 is available, the more efficiently plants can photosynthesize. There is a strong correlation between available CO2 in the atmosphere and how quickly plants can grow.
How Much CO2 Do Plants Need?
All plants need a minimum of 200 ppm (parts per million) of CO2 in the atmosphere to grow at all. Any lower and there is not enough CO2 around for the plants to absorb any. This halts growth, and can eventually kill a plant by starvation.
The average level of CO2 in the atmosphere today is 300-400 ppm. This is the level that outdoor cannabis plants receive. Increasing the amount of CO2 in your grow room can cause growth to skyrocket. Raising the CO2 concentration to 800 ppm can double your rate of plant growth.
As long as your grow room isn’t sealed, you’re not risking running low on CO2. This is just one of the reasons why having a ventilation system is important. A sealed grow room can result in CO2 levels dropping to 200 ppm in less than a day depending on the number of plants.
It is possible to give plants too much CO2, though. More isn’t always better. Once the concentration of CO2 in the atmosphere breaks 1400 ppm, plant growth slows again. In fact, at 2000 ppm, CO2 actually becomes toxic to plants. There’s a sweet spot between 800 and 1400 ppm where plant growth is maximized.
How to Supplement CO2
There are a couple ways you can supplement your indoor cannabis grow with CO2. There’s definitely an option out there for you, no matter what your budget is. An added bonus is that all of them sound like mad science. Just remember to get a CO2 gauge so you can check your levels.
When it comes to infrastructure, the simplest method of CO2 is using dry ice. Yes, the super-cold block of carbon dioxide that people use to make fog. In order to use dry ice, just put it in a shatter-proof bowl away from your plants. To raise your CO2 to 1200 ppm, follow the “Rule of 8s”. This rules states that you can use .8 lbs per 8’ by 8’ by 8’ cube of space.
Dry ice can be hard to find if you live in a rural area. It will also significantly cool your grow room, which could be spell complications for your setup.
If you can get a home-brewing kit, you can use the fermentation method of raising CO2. You’ll need yeast, sugar, and a homebrewing kit. The yeast will ferment the sugar into alcohol and CO2. There are lots of guides available to help you use this method safely.
If you don’t want to mess around with sugar or dry ice, bottle CO2 is user-friendly. These kits use pre-packaged CO2 and tubing to slowly release measured amounts of CO2 into your grow tent. No matter how big your grow tent, there’s a pressurized CO2 enrichment system on the market that will work.
Using CO2 may take a bit of time to master if you’re a newbie grower, but it’s definitely worth exploring at some point. After all, what grower wouldn’t want to increase their yields? Happy growing!