Photosynthesis is the process by which any plant, including Cannabis, produces its own “fuel”. More specifically, plants use sunlight, water and carbon dioxide (CO2) to generate sugar (a carbohydrate) and oxygen. The sugar is used by the plant, while the oxygen is expelled into the environment as a waste product.
Somewhere along the line, growers realized they could increase the yield of their crops by making more CO2 available for photosynthesis. Unfortunately, the process is not as simple as most may hope, so simply adding more CO2 is not a guaranteed way to maximize harvest quantity. Plants can only utilize the gas as long as there is enough light and nutrients available to convert it. Many growing setups only provide enough light intensity to use the CO2 concentrations available in a normal room and would not benefit from increased CO2 levels. However, with high intensity LED grow lights covering an appropriate footprint, extra CO2 can be used to increase yield. The extra light intensity allows plants to convert more CO2, as long as water is provided and the plants have enough nutrients to continue growing.
There are several ways to supplement CO2 in your grow room. Many grow shops carry products containing fungi which release CO2 for several weeks as they grow. Carbon dioxide tanks are also commonly available at grow shops along with controller systems that provide the appropriate dose of CO2 to your grow. Systems which burn propane or natural gas to produce CO2 are also available, though these also add heat to your grow room.
It is possible to raise CO2 to unsafe levels, so if you are using a burner or tanks to increase CO2 it is important to get a CO2 monitor to ensure you’re staying safe. In general 1200 ppm is a safe upper limit.
Adding CO2 definitely has potential benefits for cannabis growers, but only with the proper research and preparation.