How To Use CO2 To Increase Your Cannabis Yield

How does CO2 work?

CO2 or Carbon Dioxide is a gas present in the air and is essential for plants. While humans and animals breathe Oxygen and release CO2, plants do the exact opposite.

Plants will "breathe" CO2 through their pores and combined with light from either the sun or a grow light they will start the photosynthesis producing the energy they need to grow.

There is around 400 PPM of CO2 in the air which means your plants already access this precious resource without the need for supplementing but surprisingly, cannabis plants can thrive in environments with up to 2000 PPM. This is a remnant of another era, millions of years ago when Carbon Dioxide level was much higher in the air.

If used correctly, CO2 injection can increase yields by up to 30% and accelerate growth by 15%. 


What you need to know before using CO2

Before you start implementing this optimization there are a couple of things you should know.  

  • Supplementing CO2 is not a magical solution to improve plant yields. Proper soil/medium, nutrients, watering, light, temperature, humidity levels, and cleanliness must be achieved first. Only then will you see the improvements enhanced CO2 can provide.
  • CO2 only works in conjunction with light so you need to make sure you have enough light power already to benefit from it. This also means CO2 is useless when lights are turned off.
  • You may need to seal your grow room. This is quite easy if you have a tent, but keep in mind that if you want to significantly raise the CO2 levels of your room you first need to make sure that your ventilation setup will not automatically vent the air outside and thus waste the CO2. This is one of the main reasons using CO2 can become tricky. 
  • It can be quite expensive. Although there are cheaper solutions for smaller grows, adding CO2 to your tent can be a costly add-on especially if you intend to use a more sophisticated method such as CO2 injection or burners.
  • It can be dangerous at some point. If you plan on using very powerfull CO2 enhancer be careful because if the concentration is too high it can be dangerous to breathe.

How can you enrich your grow room with CO2?

There are many ways you can introduce Carbon Dioxide in your grow room but a lot of these options will not guarantee or monitor the exact amount of CO2 in the air. Depending on your budget you might want to consider a few options:



co2 generator

CO2 Generators: These devices will burn propane, natural gas or other combustibles and they are generally used for large grow rooms as they can produce a lot of heat. We highly recommend using these combined with monitors and controller to make sure you have the right PPM levels. Be careful as these use open flames and there is increased fire risks so make sure you choose a product that has good safety features.

co2 regulator

Compressed CO2: This is usually a bottle or a tank that will inject CO2 in your grow space. It is probably the most recommended option if you are serious about supplementing CO2 to your plants. Combined with the right monitors and controllers, it can automatically regulate the desired amounts of carbon dioxide and does not produce heat like a generator. This allows you to have better control over your temperature and removes the need for extra climatization. For this reason, it can be used in smaller grows.


CO2 Bags: This is by far the most affordable option if you want to start experimenting with CO2 and have a small grow. It uses fungi that will consume the organic matter of the bag releasing carbon dioxide in the process. Unfortunately, it is hard to calculate the exact amount produced by the bag so it is interesting to have a monitor telling you the PPM levels so that you can add the right amount of bags needed to make a significant difference.


How to use CO2 in for your grow

If you have already maxed out the potential of other variables and feel you are ready to use CO2, make sure you have good quality and powerful enough grow lights because if you don't, increasing the CO2 levels won't give you the expected results and can also damage your plants.

Most growers will recommend keeping your PPM levels between 1200 and 1800 for optimal results.

Vegetative stage: CO2 enrichment at this stage will increase the speed at which you plant grows. 

Flowering stage: CO2 is especially effective during the first 2-3 weeks of your blooming stage and tends to be less effective as you get further in the bud production. However many growers will still inject carbon dioxide up until 2 weeks before the harvest.

Make it "rain": CO2 is heavy and will tend to accumulate at the bottom of your grow space so the best way to ensure your plants can access it is to place the source at the top.

Seal your grow space or adjust your ventilation accordingly:  This is very important. If you already have a good ventilation system in place, chances are high that you have a constant air exchange. This means if you supply CO2 it will be exhausted outside and be wasted so you will need to adjust your ventilation and make sure your space is sealed to keep the CO2 available for the plants.

However, when you seal your environment, there are chances the temperature and humidity will rise above the recommended levels. The good news is that if your plants are enriched with CO2 they will withstand temperature as high as 30-35 C. Humidity resistance is also better but we recommend keeping it below 60-70% in order to avoid mold and other issues. This means you might need a dehumidifier.

Turn it OFF at night: Plant won't "breathe" during the night so make sure you don't waste CO2 and turn it OFF a little bit before you turn OFF the lights. This won't affect your results.

1 comment

Free info is always welcome. Sam, Andrew, And Chris your youtube channel is awesome! Thanks so much for all your effort. Your prices are very fair so you needless to say you will get my business.

Doug October 08, 2019

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