Use CO2 to increase yields

Carbon dioxide (CO2) is a gas that fills our atmosphere and in the air we breathe. It’s essential for plants to complete the process of photosynthesis. Photosynthesis is the process where plants convert CO2 into energy. High levels of CO2 in a cannabis garden can result in stronger plants with increased yields – if introduced correctly. Supplementing your plants with extra CO2 can increase your yields and growth by up to 20%. This post considers how you can control and add carbon dioxide to your grow room for the best possible end product.

Plant growth

Plants extract carbon dioxide from the atmosphere via the plant’s stomates, which are the pores that plants “breathe” through. Photosynthesis begins as the plant uses CO2 in combination with light to produce both sugar and oxygen. The sugar is used by the plant to grow while the oxygen is released back into the atmosphere.

CO2 and light in your grow

Increasing carbon dioxide levels in your cannabis garden will allow your plants to create more energy. CO2 can only be adequately absorbed if you provide adequate lighting as detailed in the above image. Again, light is the second requirement to create energy for your plants, meaning you must match your CO2 levels with your lighting. However, there are a number of other considerations to make before investing in a CO2 system.

Before introducing CO2 to your grow

The benefits of introducing carbon dioxide into a grow space are well known and widely accepted. However, if you’re a novice grower and/or under a tight budget, there might be a number of ways for you to initially increase your yields before investing in a costly system. Make sure you first know how to:

  • Grow a healthy garden with a quality product.
  • Prevent and/or treat mould and pest infestations.
  • Set up a secure, sealed grow space. We recommend a good quality Mars-Hydro grow tent.
  • Use an adequate high-powered light system. We recommend a good quality Mars-Hydro LED grow light.
  • Start with quality strain genetics.
  • Use quality nutrients and growing mediums.

If you have a handle on the above points, you should be ready to try increasing your yields using added CO2.

How to introduce CO2

There are multiple ways to introduce carbon dioxide to your garden, but most methods do not guarantee controlled ppm (parts per million, used to measure gas levels in the atmosphere). For this reason, it’s important to invest in a quality setup. Consider holding off on CO2 supplemented grows until you’re ready to make the jump. Especially, you haven’t exhausted other methods to increase yield as listed above.


Carbon dioxide generators, which look something like patio heaters, produce carbon dioxide by burning propane or natural gases. They can be set up to automatically power on or off when gas levels reach a specific ppm. Natural gas or liquid propane are very easy to acquire, but the burning of these gases produces heat which can be difficult to regulate in small grow spaces. Therefore, generators are better suited for large grow spaces with equipment for climate control.

Compressed carbon dioxide

Compressed carbon dioxide tanks can be acquired at hydroponic stores, compressed gas facilities, or even home brewing stores. In this case, the gas is produced by the manufacturers and is collected and compressed into tanks. This allows you to introduce controlled quantities of CO2 into your garden via emitters without having to own a CO2 generator. The benefit of this setup is that without a CO2 generator, you’re no longer producing heat when releasing CO2 into your garden. For this reason, compressed CO2 is ideal for smaller grow spaces.

CO2 for cannabis

Carbon dioxide levels in our atmosphere are around 400 ppm. Interestingly, studies show CO2 levels can continually increase plant growth as ppm reach upwards of 10,000. Note that levels above 3,000 ppm is considered dangerous for humans to breathe, and at 5,000 ppm it is considered lethal.

Most gardeners have found that when you are producing high-quality light in your garden, a carbon dioxide level of 1 200 to 2 000 ppm will increase the growth of your plant significantly. Additionally, when using CO2 your plants can handle a higher average temperature. Be aware that if your CO2 levels are too high for the amount of light or heat generated in the garden, you will see your plants become damaged from excess levels.

The carbon dioxide emitted should ideally fall from above the garden, as the gas is heavy and will sink to the ground. Using fans will help keep the CO2 moving around the room and make it available for more plants to absorb. CO2 should only be emitted during the time that the lights are on; plants photosynthesize while it is dark out.

Growing cannabis is an ever-changing practice. Taking on a challenge such as introducing carbon dioxide could evolve your garden, taking it to the next level.