CO₂ for Plant Growth

Any good grower can tell you nutrients make a big difference in your yields. That said, not all nutrients, or elements, come in the same forms. For example CO₂, or carbon dioxide. You don’t add CO₂ to your nutrient solution, but if you do add it to your grow area, it can make a big difference. There are plenty of things you should know about using CO₂ for plant growth, and in this guide we’ll go over the basics.

 Why do Plants Need CO₂?

Plants use photosynthesis to create the energy, or ‘food’, they need to grow. Another part of this process is respiration, wherein plants release oxygen and water vapor. This allows plants to maintain a stable internal balance, and continue taking in water and nutrients. What you might not know is that CO₂ actually plays a vital role in both of these functions. 

In essence, photosynthesis is both a physical and chemical reaction within the plant. Plants can take carbon dioxide, CO₂, from the air. They absorb CO₂ through the stomata in their leaves. Once this compound meets the water, or H₂O, within the leaves, it’s almost ready to use as food. However, plants also need sunlight (or a good grow light) to serve as the catalyst for this transformation.

 In short, without CO₂, plants can’t really feed themselves. 

A CO2 molecule consists of one carbon atom, and two oxygen atoms

Using CO₂ for Better Plant Growth

Now that we know CO₂ is a critical component for plants to produce their own energy, we can see how it helps them grow. However, adding a little extra CO₂, even if your growing area isn’t short on it, can give them a boost. Think of it more like, the more you eat, the more you can grow. Naturally, there are certain limitations to this. Any creature will suffer with too much CO₂, so you need to be conscious of how much you add. 

Normal ambient conditions

Under most normal conditions, the CO₂ concentration in the air is around 410 PPM (Parts Per Million). There’s nothing wrong with this level, and your plants can grow normally, provided that they get everything else they need. This is a safe level for plants, animals, and humans. Plus, no matter what your lighting cycle is, 410 PPM of CO₂ doesn’t increase or decrease plant growth.

Raising CO₂ for bigger yields

410 PPM might be the normal ambient CO₂ level, but you can actually raise it quite a bit higher to improve plant growth. Some growers and agriculturalists even suggest raising levels to up to 1000 PPM. However, with many plants, going too far above this level can deprive them of other elements they need, and ultimately lead to stunted growth. 

In fact, some studies show that raising CO₂ to over 1300 PPM can cause the same decrease in growth as if you had a low CO₂ concentration. Going above this level essentially reduces growth rates to nearly the same level as if your CO₂ were at 200 PPM or below. Again, this applies regardless of your lighting, lux levels, par readings, or other factors.

Methods of adding CO₂

There are plenty of ways to add CO₂ to your grow area. You can use any of these methods, as long as you apply them properly, and monitor your CO₂ levels. Common ways to supplement CO₂ for plants include: CO₂ generators, CO₂ bags, kits, and pressurized canisters. You should always have a testing system in place to ensure everything works properly, and to avoid health and safety issues for yourself and others. We’ll cover each method of adding CO₂ in depth later, but for now, it’s important to understand the basic principles of how it all works. 

Important notes

CO₂ is a great way to enhance plant growth. However, it can also be a big problem if you don’t use it properly, or if your system or grow area has a leak. Always use caution when working with CO₂, and follow manufacturer directions exactly. It’s far better to start with a lower level, and gradually raise it as you become more experienced working with CO₂ for plant growth. 

Carbon dioxide isn’t something you can smell leaking out of your grow area. It’s the same as if there were a CO₂ leak within your home. Always keep CO₂ detectors around your living areas, and regularly check your CO₂ system for any issues or defects.