How to add CO2 to your indoor cannabis grow

How to add CO2 to your indoor cannabis grow
Luke Sumpter

When growing indoors, added CO₂ can help promote growth and increase the yield of your cannabis plants. Read more on CannaConnection to learn more.

Growing cannabis indoors can be challenging, and cannabis cultivators are always on the lookout for new and improved ways to get the most out of their plants.

In this article we look at how to use CO₂ to increase your indoor cannabis yields. For more articles like this and the latest cannabis-related news, remember to bookmark our site and check in with us regularly.


Before we look at specific ways to increase the CO₂ levels in your grow area, it’s important that you understand how plants use CO₂ in the first place.

Carbon dioxide is a colourless, odourless gas that is vital to life on earth. It is particularly important for plant growth as it plays a central role in photosynthesis.

Plants absorb CO₂ from the environment through stomates (tiny pores found in the plant’s epidermis). During photosynthesis, plants use a combination of carbon dioxide and the energy from the sun (or another light source) to produce sugar and oxygen.

While the oxygen is released back into the environment, the plant uses the sugar to fuel its growth. Hence, by increasing the amount of CO₂ in the atmosphere, you can potentially boost the growth rate of your plant’s and simultaneously drive up their yields.


Adding CO₂ into your indoor cannabis grow area is a relatively complex procedure that requires some specialized equipment. Hence, we usually suggest you forget about experimenting with CO₂ until you’ve got some decent grow experience under your belt.

If you’re looking to increase the yield of your cannabis plants, there are a variety of simpler methods you might want to try before you decide on adding extra CO₂ to your grow.

First and foremost, you’ll want to make sure you’re growing healthy plants before you think about trying any sort of advanced grow techniques. Make sure you check out our other grow articles and begin building up your skills to ensure you have a solid understanding of how cannabis grows and how to push your plants to their full potential.

Secondly, you’ll also want to make sure you’ve invested in a professional grow space prior to investing in a CO₂ kit. Your grow area will need to be secure and sealed prior in order to avoid any extra CO₂ from escaping, and you should also be using a quality lighting and ventilation system, as well as top-shelf strain genetics and nutrients.


Once you’re confident you have decent grow experience and a professional set up, you’re ready to try increasing your yields with added CO₂.

Remember, for best results you’ll want to invest in a quality kit that allows you to measure the ppm (parts per million) of the CO₂ in your grow space. Without an exact idea of how much CO₂ is in the atmosphere, it is virtually impossible to measure whether your plants are getting the right amount of exposure.

CO₂ levels in our atmosphere average around 400ppm. The ideal CO₂ levels to increase the yield of cannabis plants is roughly 1,200 to 2,000ppm. Studies show that CO₂ levels of up to 10,000ppm can still significantly increase plant growth. However, managing a grow space with such high concentrations of CO₂ is difficult as CO₂ levels over 3,000ppm are dangerous to humans, and concentrations of roughly 5,000ppm are considered lethal.

The two most popular ways of introducing extra CO₂ to your cannabis grow include using CO₂ generators or tanks (which we will explore in a bit more detail later).

Ideally, extra CO₂ should enter your garden from above. The gas is heavier than oxygen, so it will naturally sink to the floor. You should also use fans or a ventilation system to ensure the CO₂ is spread evenly across the room.

Remember to introduce your extra CO₂ gradually and to keep a close eye on how your plants respond. You’ll also want to increase your light sources and temperatures (to roughly 29-32°C or 85-90°F) or your plants will get damaged.

Excess CO₂ should always be added to your garden when the lights are on and your plants are photosynthesizing.

The two most popular ways to add extra CO₂ to your cannabis grow area rely on CO₂ generators or tanks.

CO₂ Generators: CO₂ Generators look similar to patio heaters and burn propane or other natural gases in order to produce carbon dioxide. It’s important to note that they produce extra heat, which can be hard to regulate, especially in small areas.

CO₂ Tanks: CO₂ tanks contain compressed carbon dioxide that can be readily released into the atmosphere. They are ideal for smaller grow ops or for growers who don’t want the extra hassle of producing their own CO₂ with a generator.

To ensure you get the best results from your CO₂, you’ll want to make sure you’re able to easily and accurately measure the carbon dioxide levels in your grow area.

The easiest way to do this is to invest in a CO₂ meter. The most basic models start at about €110.

Indoor growing is becoming more and more popular for a variety of reasons, including legal issues and space constraints. Whatever the reason, if you’re looking to max out the potential of your indoor plants, we highly suggest experimenting with CO₂ levels.

Luke Sumpter
Luke Sumpter

Luke has worked as a cannabis journalist and health science researcher for the past seven years. Over this time, he’s developed an advanced understanding of endocannabinoid system science, cannabis phytochemistry, and cultivation techniques.