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How to Use CO2 to Boost Cannabis Growth at Home

For many people working in a sealed grow space, the number one goal is to get plants to grow big, to increase yields, and to make the most out of any growth space. With that being said, many people don’t know how to make the most out of their grow rooms to make their cannabis plants produce the highest yields.

Well, one way to increase cannabis yields at home is to use a natural gas, carbon dioxide, to spur on plant growth. Using CO2 for lead growth is quite common, especially if you are working in indoor grow rooms that allow for great environmental control.

It’s all about raising CO2 levels to allow for proper plant growth. If you don’t really know what carbon dioxide is or how it affects plant growth, no worries, because this is something we will discuss below.

However, the bottom line is that if you are growing cannabis, no matter the growing environment you are in and aside from other factors, if you add CO2 to the equation, you should see your plants growing faster, bigger, and producing much larger yields.

Having some CO2 tanks in that room will most certainly give your cannabis plants a big boost. Home growers everywhere know that carbon dioxide is a very important part of plant respiration, and it can make a big difference. Let’s take a closer look at how exactly to use carbon dioxide for weed growth.

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What is Carbon Dioxide?

Carbon dioxide or CO2 is an odorless and colorless gas that is composed of a single carbon atom which is bonded to two oxygen atoms. This is a naturally occurring compound and is a part of the atmosphere of earth, where it plays a very crucial role in supporting life and maintaining the plan’s temperature.

Carbon dioxide is produced through a variety of natural processes, such as volcanic eruptions, the decay of organic matter, and respiration of animals. It also happens when fossil fuels are combusted or natural gas is burned. CO2 is absolutely essential for plant photosynthesis, so you can see how it might be important for weed growth.

Plants use sunlight to convert carbon dioxide and water into oxygen and glucose, which they need to grow. This is also very important for producing oxygen for the rest of us humans to breathe. With that being said, keep in mind that CO2 is a greenhouse gas, so it serves to heat up the earth’s atmosphere by trapping heat.

Why is CO2 Good for Plant Growth?

Having proper CO2 levels in your grow room is very important for a number of reasons. The benefits of CO2 for growers are huge! First and foremost, as mentioned above, all weed plants require carbon dioxide to engage in photosynthesis.

This is the process where carbon dioxide and water are converted into oxygen and glucose, which the plant then uses as a source of fuel. This is the foundation of the cannabis plant’s process of growth and production. Photosynthesis cannot happen without carbon dioxide.

On that note, when there are elevated levels of CO2, photosynthetic inefficiency increases drastically in plants. The reality is that in our normal environment, plants don’t get quite enough CO2 to engage in the most efficient photosynthesis possible.

However, if you add CO2 into a grow room, you can greatly increase the growth rate and productivity of any plant, cannabis or otherwise. However, there’s more to it than just that.

For instance, all carbohydrates, proteins, and fats found in plants use carbon as their building blocks. Carbon dioxide provides plants with these essential building blocks, and it also allows for enhanced plant growth through the increased production of even more carbohydrates, therefore resulting in much bigger roots, stems, and leaves.  In general, cannabis plants respond very positively towards adding CO2 into a sealed grow room.

If a plant has bigger roots, it means it can uptake more nutrients from the soil, and if it has more leaves, it can intake more sunlight from your grow lights, both factors which will lead to faster and bigger growth. On that note, when cannabis plants get higher CO2 levels, it can also improve their overall water use efficiency. In other words, your plant can grow with less water.

Overall, CO2 in the form of CO2 enrichment is a technique often used for increasing plant productivity and plant growth in agricultural settings, and it works for weed as well. When it comes to adding CO2 to your grow room, it’s beneficial for vegetative growth and the flowering stage alike. Cannabis cultivation can greatly benefit from some added CO2, and this is true for every one of the plant’s growth stage.

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Is Using CO2 for Weed a Good Idea?

Let’s take a quick look at why exactly you might want to add CO2 into a grow space when cultivating cannabis. The simple reality is that using carbon dioxide to grow cannabis is a very good idea, and this is true for a number of reasons.

As mentioned above, when plants receive elevated levels of CO2, they generally have increased productivity and growth rates. They grow faster, bigger, and stronger, complete with healthier stems, roots, and leaves. As you can tell, this can be beneficial for cannabis in a number of ways.

The leaves, roots, and stems of the plant are all vital in their own ways. On that note, plants that are exposed to elevated CO2 levels generally have better nutrient uptake as well. This leads to more nutrient rich and much healthier cannabis plants.

Furthermore, you are also likely to need less water when growing cannabis with CO2, and at the end of the day, you’ll most likely see highly increased yields.

What many people may also not know about growing cannabis with elevated CO2 levels is that the plants may actually mature much faster, which could reduce the time it takes to get from seed to harvest. As you can see, indoor growers can greatly benefit from high concentrations of CO2

Best Carbon Dioxide Levels for Weed Growth

OK, so something that is very important to note here is that cannabis plants, although they require elevated CO2 levels to grow efficiently, don’t need the same amount of CO2 in every growth stage.

Every one of the cannabis plants growth stages, whether seedling, vegetative growth, or the flowering stage, requires slightly different CO2 levels in order to maximize overall growth rates and efficiency. Let’s take a quick look at exactly how much CO2 a cannabis plant needs according to the growth stage.


During the seedling stage, CO2 levels between 400 parts per million and 800 parts per million will do just fine. At this stage, there is generally no need for highly elevated CO2 levels. The CO2 levels listed above should be more than enough to allow for a good branch and beef development.

Vegetative Stage

If you are looking to increase plant development and growth rates, when the cannabis plant enters its vegetative stage, you can increase the CO2 levels up to 1200 parts per million. This should allow for great leaf, root, and stem development, everything cannabis plants needs during its vegetative stage. Remember, it’s all about using photosynthesis to allow for massive foliage growth during this stage.

Flowering Stage

The flowering stage is when you’ll want to add the most CO2 into any grow room. Your grow room can greatly benefit from CO2 levels up to 1500 PPM, with some even going as high as 2000 PPM for very short periods of time when the lights are on. When it comes to increasing bud production and the yield of your cannabis plants, this is by far one of the most important things that you can do.

Early Harvest

You could also maintain high concentrations of CO2 in an indoor grow space all the way to harvest time. Having elevated CO2 levels in the grow room will help to increase overall trichome and resin production.

How to Use CO2 for Cannabis Plants in a Grow Room

Now that you know why adding CO2 into a cannabis grow room is so important, let’s figure out some of the best ways to do so. After all, you need the right equipment to add CO2 into a grow space. Let’s figure out how it’s done.

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CO2 Generators

One of the most common ways to add CO2 into an indoor growth space is to use a CO2 generator. First, this could come in the form of an ethanol alcohol generator, which works by evaporating ethanol to produce CO2.

However, this is not quite as common as a natural gas or propane generator, which burn either natural gas or propane to produce carbon dioxide. These come in many different sizes to suit different grow rooms, and they generally come with thermostats or CO2 controllers to regulate the production of CO2.

Compressed CO2 Tanks

Compressed CO2 tanks, otherwise known as CO2 cylinders or CO2 bottles, are full of pure CO2. These are tanks that have a flow meter and a regulator that allows cannabis cultivators to easily control the release of exact CO2 levels into a grow room. CO2 tanks are perhaps some of the most commonly used pieces of equipment to elevate carbon dioxide levels in a grow room.

CO2 Pads or CO2 Bags

CO2 bags are special little bags that are full of enzymes and fungus that create carbon dioxide as they breakdown. Remember, the breaking down of organic matter is one of the biggest producers of carbon dioxide. If you have a small growth space or just need some supplemental CO2, then a CO2 bag can be very beneficial. There are also CO2 pads, which are great for small grow areas.

CO2 Enrichment Systems

CO2 enrichment systems, otherwise known as liquid CO2 systems, use liquid carbon dioxide that is currently in a gas form and is then released into a grow room using a strictly controlled and monitored systems. This is one of the more advanced ways to add CO2 into a grow room, as you can add very precise levels. They often come with monitors that tell you the exact parts per million currently in the air.

CO2 Enhancement Machines

Yet another way to add CO2 into a grow room is to use a so-called CO2 enhancer. These are very similar to the propane and natural gaspers which we discussed above, albeit more advanced and more expensive.

These use natural gas or propane as a fuel source, which burn the gas and therefore release carbon dioxide. They also come with controllers and sensors so you can maintain optimal CO2 levels for your indoor grow space.

Using Dry Ice

Although it’s not nearly as common as some of the other methods discussed today, using dry ice to supplement CO2 into a grow room is an option. That said, it’s hard to control exactly how much is released.

Tips on CO2 Cannabis Supplementation

Before we call it a day, let’s go over some quick tips on supplementing your cannabis plants with CO2.

  • Always choose the right or best method of CO2 supplementation for your circumstances. We recommend doing a bit of research into each method first.
  • Always use a high quality and reliable CO2 monitor so you know what the exact PPM level is currently like.
  • Keep in mind that CO2 is only required when photosynthesis is happening, which means that the grow lights have to be on. Therefore, using a controller or timer to regulate when you inject CO2 into a growth space is crucial. Injecting CO2 into a growth space when it is dark is completely useless.
  • You also want to use some fans to create some air flow so that the CO2 is properly distributed within the row space.


At the end of the day, one of the absolute best thing that you can do for your cannabis plants is to provide them with as much carbon dioxide as they need to grow big, strong, and healthy.

Fabian Raemy is an avid cannabis enthusiast and expert. He's been a part of the cannabis community in one way or another for the past 15 years. Whether cultivating or consuming, Fabian knows his cannabis inside out. In his humble opinion, there’s just nothing more rewarding than growing a great strain of marijuana and being able to take a puff of some home grown green.

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