The Basics of CO2

The Basics of CO2

Below is some basics you should know about CO2:

Plants require carbon dioxide (CO2) to conduct photosynthesis. You can enrich atmospheres with additional CO2 to sustain and increase plant growth. A photosynthesis-related drop (by a factor less than two) in carbon dioxide concentration in a greenhouse compartment would kill green plants, or, at least, completely stop their growth. At very high concentrations (a factor of 100 or more higher than its atmospheric concentration), carbon dioxide can be toxic to animal life, so raising the concentration to 10,000 ppm (1%) or higher for several hours will eliminate pests such as white-flies and spider mites in a greenhouse.

CO2 is made up of one carbon molecule and two oxygen molecules that are in a gaseous form at standard conditions for temperature and pressure. But enough of the elementary science, how is it important to your plants ? The role of CO2 is not a complicated one to understand, photosynthesis is a process that all plants use to converts carbon dioxide into organic compounds, especially sugars, using the energy from light. Now what this means to you is that your plants require CO2 to make food for themselves, pretty simple. Not so fast.

Where is it? In the very air you are breathing right now. With that being said, why would you need CO2 at amounts greater than what is in the air? Good question. Let’s break the explanation down.

CO2 in the air is at about 400-450 ppm (parts per million). At first glance that seems to be pretty damn good, after all if plants outside can survive quite nicely on that concentration why mess with it indoors? The primary reason for increasing CO2 levels is plant growth. Recall that CO2 is used to make food for your plants, increase the supply of what makes food and you have bigger plants.

Now like all things, moderation is key, there comes point where you can have too much CO2 in the environment and actually damage your plants. The most serious impact of excess CO2 is to reduce the plant’s stomas opening. Why is this important? Stomas, in the botanical sense, are pores in plants which allow the plant to breathe or transpire. This reduced opening results in less CO2 absorption and less transpiration.

Transpiration is a key process for plants because water and nutrient absorption depends on it. Now what is transpiration? It is like sweating but for plants, in laymen’s terms. In your hydroponic system, the nutrient solution is absorbed by the roots, it travels up the plant and the extra water that the plant does not need is released by the stomas. That is transpiration in a nutshell. There is more to the process than that, but for our purposes we only need to illustrate the concept. About 90% of the water that enters a plant’s roots is used for transpiration.

So that brings us to humidity as a result of increased CO2 in your grow system’s environment Think of it in these terms. Your plant is in optimal growing conditions, what does it do? It grows like mad. With that increase in growth there is an increase in the byproducts of photosynthesis, mainly water and oxygen via transpiration. You do need to watch for the increase in humidity as it can allow for the growth of fungi and no one wants that in their grow room. Good ventilation is vital for plants growth and the prevention of fungi..

You will also need to pay close attention to your growing environments temperature. When you “enrich” your crop with CO2 you need to adjust the temperature as well. As much as 13oC (8oF). Just keep in mind that the plant’s metabolism works much faster when exposed to that “enrichment” so all your crops requirements will increase as well. CO2 as an addition can increase your yields and be a benefit to your crop done properly. Having said this, if you are just starting out in the wonderful world growing, CO2 enrichment is something that is not absolutely vital to your system. My recommendation is not to jump into CO2 enrichment without proper research.


Here are some methods of creating C02 that I know of, if anyone knows any other methods please feel free to share.

C02 tank with a drip release system (pressure regulator). You can use any CO2 tank for this, used welding tanks can usually be found the cheapest. CO2 via tank is recommend for mid-lg sized grow setups.

Mixing water with Dry ice.

Mixing a few cups of vinegar with a few tsp of baking soda will create CO2. This can be beneficial in small growing areas.

Mixing water, yeast, and sugar will also create CO2. This is also beneficial in small growing areas.

Spending a little bit of time in the greenhouse will also increase CO2 levels. Just breathing in your greenhouse will create CO2, but singing will create even more!