Understanding CO2 Injection in Cannabis Cultivation

Carbon dioxide (CO2) is a vital component of photosynthesis, the process through which plants use sunlight to convert carbon dioxide and water into glucose, which they use for energy. In addition to providing energy for plant growth, the photosynthesis process also releases oxygen into the environment. In the context of indoor cannabis cultivation, CO2 enrichment or injection is a technique used to increase the quantity of CO2 in the grow area, aiming to enhance the rate of photosynthesis and thereby boost plant growth and yield.

The Importance of CO2 in Cannabis Cultivation

Photosynthesis, as mentioned, is the lifeblood of all green plants, including cannabis. In this process, plants take in CO2 from their environment and, through a complex series of reactions driven by sunlight, produce glucose as an energy source. This is vital to the survival and growth of the plant. Typically, the concentration of CO2 in normal atmospheric conditions is about 400 parts per million (ppm), but cannabis, like other plants, can benefit from higher concentrations.

Cannabis can utilize CO2 levels up to 1,500 ppm in its environment, which is nearly four times the concentration found in Earth’s atmosphere. When properly implemented, CO2 enrichment can result in faster growth, larger yields, and more robust plants. This is why many cannabis growers, especially those operating indoors, are interested in CO2 injection.

The Science Behind CO2 Injection

The principle behind CO2 injection is quite straightforward. Plants, including cannabis, grow by using sunlight (or artificial light in indoor growing conditions) to combine CO2 and water into sugars, which provide energy for growth. By increasing the concentration of CO2 in the environment, the plants can process more sugars and thus grow at a faster rate.

However, it’s important to remember that CO2 is only one of the many factors that affect plant growth. Light, water, temperature, and nutrients are all essential, and none of these factors can be neglected in favor of another.

Implementing CO2 Injection in Cannabis Cultivation

Implementing CO2 injection in an indoor cannabis cultivation system requires careful planning and execution. There are several ways to increase CO2 levels in a grow room, such as burning propane or natural gas, decomposing organic matter, or using a CO2 generator.

When designing a CO2 injection system, the following considerations are crucial:

  1. Concentration: CO2 levels should ideally be maintained between 1,000 and 1,500 ppm for the most beneficial results. This is best monitored with a CO2 meter.
  2. Ventilation: An enclosed space is required to maintain high CO2 levels, but sufficient ventilation is necessary to prevent overheating and to supply fresh air.
  3. Distribution: CO2 is heavier than air, so injection points should be placed above the plants, ensuring CO2 filters down over them.
  4. Timing: Plants only use CO2 during the light phase of their cycle when photosynthesis can occur. Thus, CO2 should be injected during the light hours and reduced during the dark phase.
  5. Temperature: Higher temperatures (up to 30-32°C or 86-90°F) can enhance the effect of CO2 enrichment. However, temperatures should not exceed this range as it can lead to plant stress and damage.

Risks and Considerations

While the benefits of CO2 injection can be significant, it’s not without risks and considerations. CO2 enrichment requires a substantial investment in equipment, including CO2 generators or tanks, monitoring systems, and enhanced climate control capabilities. Additionally, the complexity of maintaining an ideal growing environment increases, as growers must also manage higher temperatures and balance other factors like light intensity and nutrient levels.

From a safety perspective, CO2 is non-toxic, but it can displace oxygen in an enclosed space, which can be harmful to humans and pets. CO2 levels above 5,000 ppm can be unhealthy for humans, and levels above 15,000 ppm can be lethal. Therefore, careful monitoring and safety precautions, including proper ventilation, are essential when implementing a CO2 injection system in a cannabis grow room.

Lastly, while CO2 injection can enhance cannabis growth and yield, the technique is most effective when other growth conditions are already optimal. It’s important for growers to ensure they’re already providing sufficient light, nutrients, and water, and maintaining proper temperature and humidity levels, before considering CO2 injection.


CO2 injection can significantly enhance cannabis growth and yield, making it an enticing technique for indoor cannabis cultivators. However, it’s a method that requires careful implementation and a balancing of various other growth factors. For growers considering CO2 enrichment, a thorough understanding of the cultivation process, robust monitoring systems, and diligent safety measures are crucial for achieving the desired benefits.