Carbon Dioxide (CO2) is a chemical compound that fills the atmosphere in a gas state and is essential for healthy plant growth. Together with water and sunlight, carbon dioxide plays an important role in crops to create sugars and oxygen.
Cannabis plants, like all plants, use carbon dioxide during photosynthesis to produce energy and oxygen. In fact, carbon dioxide is one of the primary building blocks of plant tissue. However, cannabis plants and CO2 have a delicate relationship. While they need the gas to develop optimally, an excess could ruin the crops and damage the buds before they’re mature enough to harvest.
Benefits of CO2 for cannabis cultivation
Increasing the concentration of CO2 in the air around cannabis plants can help promote faster growth and higher yields. This is because photosynthesis is directly linked to the amount of CO2 available to the plant. By increasing the concentration of CO2 in the air, growers can help cannabis plants produce more energy, which can lead to larger and more abundant flowers.
Typically, cannabis plants thrive in an environment with a CO2 concentration of around 1000 parts per million (ppm), which is higher than the natural concentration in the atmosphere (around 400 ppm). Some growers use CO2 supplementation techniques, such as introducing CO2 gas into their growing environment, to raise the concentration of CO2 and boost plant growth.
However, it’s important to note that while CO2 can be beneficial for cannabis growth, excessive amounts of CO2 can be harmful to humans and the environment. Additionally, the use of high levels of CO2 in the cultivation of cannabis plants can be costly and energy-intensive. It is important for growers to balance the benefits of CO2 supplementation with the potential risks and costs.
How to enrich your CO2 using LED lights
Optimum CO2 levels for growing cannabis under high-PPFD (Photosynthetic Photon Flux Density) lights often range from 400-1400 ppm and depend on the plant’s growth stage, as well as the light intensity and air temperature. As plants grow throughout the production cycle, the increasing light intensity will promote higher rates of photosynthesis, which is ideally supplemented by increasing CO2 levels to enhance the photosynthesis process. At PPFD of _> 500 umol/m2/s, the recommended CO2 levels should be _> 800 ppm (Figure 1).
Temperature also plays an important role in accelerated gas exchange. High-PPFD light and high CO2 concentrations must pair with higher temperatures to balance transpiration rates associated with wide-open stomata. For instance, some cultivators may run 1,400 ppm/1,000 umol/m2/s while keeping their room temperature at 75° F (23.9 C), which limits the benefits of CO2 enrichment and supplemented photons. In the reproductive phase of growth, temperatures as high as 84° F (23.9° C) are recommended, and some growers may even find 90° F (32.2° C) acceptable. 
In conclusion, while CO2 plays an essential role in cannabis cultivation, it is important to understand the balance of benefits and potential risks of too much CO2. The use of PPFD lights can also help to increase rates of photosynthesis which can lead to maximizing growth.
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