How does CO2 work for cannabis plants?

The signs of carbon dioxide deprivation

The benefits of introducing CO2 to your grow room

How to use CO2 to get high yields

Best ways to add CO2 to your cannabis garden

CO2 and cannabis


Do you want to optimize your crops to produce colossal yields of cannabis? CO2 may be the solution. Carbon dioxide plays a crucial role in the plant's development and may contribute to better-quality buds and a bigger harvest.

CO2 is readily available in the atmosphere and is a product of human respiration. Adding it as a supplement in your grow room could benefit your crops.

Are you ready to learn more about how CO2 for weed can affect your yields? Keep reading to discover the advantages of carbon dioxide for cannabis, how to add it to your grow room, and how to use it. 

Let's dive in.


How does CO2 work for cannabis plants?

Incorporating CO2 in the grow room setup helps with multiple processes. It plays a critical role in the healthy growth of marijuana plants. 

The three life processes carbon dioxide affects are:

  • Respiration: Whether you’re growing weed indoors or outside, carbon dioxide is necessary. Plants ingest it through their pores, known as stomata, to facilitate “breathing” and initiate photosynthesis.
  • Transpiration: Crops lose water through transpiration. Using CO2 for cannabis helps plants retain moisture by minimizing how much H2O escapes. The stomata only open a little when there’s enough carbon dioxide, lowering the transpiration rate. It’s easier for nutrients to get adequately distributed.
  • Photosynthesis: This process is vital for all plants and one of the biggest reasons why using CO2 for growing weed affects bud quality. Crops use light to convert water and CO2 to sugar. They then emit oxygen as a byproduct.


Cannabis and CO2


The signs of carbon dioxide deprivation

How do you know when marijuana crops aren't receiving adequate carbon dioxide? Several signs indicate the crops need more CO2, including: 

  • Slow growth
  • Yellowing leaves 
  • Gangly branches

All aspects weaken as the plant can't perform photosynthesis properly without CO2. If left unchecked, the weed crops may die. 

Too little carbon dioxide means the plant can't perform vital life processes, but an excess is also detrimental. CO2 and marijuana require a delicate balance. 


The benefits of introducing CO2 to your grow room

There are multiple benefits to supplementing your weed crops with this odorless gas. Here are several reasons why you should introduce CO2 to marijuana plants: 

  • Crops grow faster and have better health: When photosynthesis occurs optimally the plant flourishes.
  • Larger yields: Combining CO2 and cannabis allows the crops to produce at their peak. 
  • Improved temperature support: Crops aren't as sensitive to heat when they have an adequate supply of carbon dioxide. 
  • Smell reduction: Some of the equipment required for CO2 supplementation helps mask the aroma of cannabis. 
  • Better security: To successfully implement CO2 for cannabis plants, you must seal the grow room. Your crops are secure and safe from theft or animal damage. 


How to use CO2 to get high yields

Cultivating outdoor weed seeds means you have to rely on mother nature for your CO2 requirements. Using carbon dioxide indoors requires a bit of research. Several factors need to be in place when growing weed with CO2. 


What time is the right time?

Cannabis crops go through four phases of development. The first one is germination, where your weed seeds sprout roots. The second is where your plant develops leaves; during the third, the most rapid growth happens. The final phase is when the crops produce buds.

CO2 for weed plants is most beneficial during the vegetative and flowering phases. During the former, carbon dioxide helps with plant development, allowing them to grow faster and more robustly.

During the final growth phase, carbon dioxide helps plants produce healthy buds and big yields. There's a debate among growers about whether to only supplement during the early stages of flowering or continue until two weeks before harvest. 

Cultivators agree that the CO2 levels during flowering can impact how big the yields are.


Calculating the needed amount of CO2

The amount of carbon dioxide depends on various factors, but the most important is the type of lights for marijuana growing. A safe quantity ranges from 4001500 PPM.

The appropriate quantity depends on how much light is in your growing area, measured in lumens per square meter. Displayed best in a table: 



Light Intensity (Lux)

Safe Carbon Dioxide Levels (PPM)









Preparing a grow room for CO2

How much does CO2 increase weed yields? It depends on the other growth factors. Before adding carbon dioxide to the cost of growing marijuana, make sure your grow room is up to standard. Factors to look at include: 

  • An appropriate lighting system
  • A hygienic environment 
  • No signs of pathogens, pests, or disease 
  • Premium soil and nutrients 
  • Healthy pH levels 
  • A sealable grow room 
  • Hardy, healthy cannabis strains

You need the proper equipment to set the ideal temperature and humidity for a cannabis grow room.


Monitoring the amount of CO2

Now that you know how to implement CO2 for weed, you must understand the importance of monitoring it. If the levels fluctuate, it may impact the health of your crops. 

Invest in a CO2 meter to maintain the appropriate levels of carbon dioxide. Various options are available, and some offer remote monitoring systems with sensors. Others may even notify you when you’re out of range by email or text message.


Cannabis and CO2


Best ways to add CO2 to your cannabis garden

What does CO2 do for weed plants? It facilitates healthy growth if you implement the supplementation correctly. There are several ways to add carbon dioxide to your marijuana garden. Some options include:


CO2 generators

Carbon dioxide generators are straightforward to use. They work with propane or natural gas and may give off heat. Some generators have integrated timers for automated use.

A CO2 generator for cannabis is best in larger cultivation areas, like a greenhouse. We don’t recommend this option inside your home, as it can be dangerous due to carbon monoxide emissions.

Some growers make DIY generators. This method requires sugar, baking powder, and dry, active yeast. Add these ingredients to boiling water, and the waste product is CO2. The solution emits the gas at a steady rate.

After a while, the alcohol kills off the yeast, and you need to replace the batch. 


Compressed CO2

Opt for compressed CO2 tanks in smaller spaces. Manufacturers make this carbon dioxide product and keep it in tanks. 

Compressed CO2 tanks are straightforward to apply and don’t generate any heat. To optimize their use, purchase additional equipment that helps with automation. Products include: 

  • A doser 
  • Pressure gauge 
  • Flow meter
  • Timer

When growing weed with CO2, use a regulator to control the PPM levels. These tanks are cheaper than generators and offer the same amount of control.


CO2 bags

Cultivators who use a hydroponic setup favor this option. CO2 bags for weed plants are deemed safer than other alternatives as they don’t have wiring and tubing. The bags provide a steady stream of carbon dioxide and don’t need any additional equipment. 

CO2 bags typically get activated by light and heat because of their mycelium material. They swell and gradually diffuse carbon dioxide. 

They’re the ideal way to release CO2 for cannabis plants for domestic growers who don’t have space for heavy equipment.

Ensure that you hang the bags far from your fans or direct intakes and outtakes, as these can cause the gas to sink quickly. 


Dry ice

Dry ice is solid carbon dioxide, and you can use it for supplementation in your garden. The method is quite labor-intensive, and many growers find it impractical. Wear isolated gloves, break the dry ice into small pieces, and scatter the bits around your plants.

There are some downsides associated with this method. The ice melts quickly, and you don’t have control over how much CO2 is released at once. You can’t automate this form of supplementation, and it can be expensive in the long run.


Baking soda and vinegar (DIY)

A DIY carbon dioxide generator offers an inexpensive way to incorporate CO2 into your grow room setup. It only requires vinegar and baking soda. Combining the two components creates a chemical reaction, resulting in CO2.

For an effective method, some cultivators set up a drip system that causes the vinegar to drop gradually into the baking soda. The result is consistent carbon dioxide release. 

This system can’t be accurately controlled, and you need to monitor the levels in your grow area. 


CO2 and cannabis

Using CO2 for weed gives you various advantages. It enhances the growing experience and delivers healthier plants that produce bigger harvests

Crops that receive this supplement have luscious foliage with a sturdy structure. The security of your plants is better, but you must keep your growing area immaculate.

The main drawback of using carbon dioxide for cannabis is the cost. If you're serious about producing premium weed, it’s a worthwhile investment.

Now that you know how to use CO2 for marijuana plants, why not browse our SeedSupreme strain catalog and find a cultivar you love?

Posted in: All Cannabis NewsWatering and Nutrients