The benefits of CO2 enrichment on indoor grow operations are already widely recognized throughout the growing community. However, the best way to apply and use CO2 is often debated amongst growers.
In the following article, we’ll take a closer look at air circulation, CO2 uptake inside your grow room, and the ideal CO2 levels for growing plant. If you have been looking at CO2 as an option for your grow room, this article should give you the guidance you need to find the ideal levels for maximum benefit.
How Does Plant Use CO2?
The most common way that plants fix carbon is known as C3 photosynthesis. All crops which benefit from CO2 fertilization generally follow the same path. Imagine that plants are made up of small reaction sites stacked on top of each other. These small spaces harness raw materials and light and then turn them into an energy-rich block that the plant uses as fuel. One of the key ingredients in these small building blocks is CO2.
These CO2 molecules need to be sent efficiently throughout the plant to allow the photosynthesis process to occur. RuBisCO binds with CO2 molecules and sends them on their journey towards photosynthesis. The limiting factor in this process is the RuBisCO. When the temperature or light intensity exceeds the plant’s tolerance levels, the RuBisCO can’t keep up with CO2 demands, and the plant is placed into a stress mode.
Suppose you can add additional CO2 into the process. In that case, you boost the effectiveness of the RuBisCO, making it more efficient, allowing the plant to boost productivity, and avoiding putting excessive stress on the plant.
CO2 Uptake and Air Circulation
As the RuBisCO uses up the CO2 present in the leaf of the plant, more CO2 is absorbed. CO2 enters the leaves of the plant passively through small pores known as stomata. If you have poor circulation or low levels of CO2 inside your grow room, the plant isn’t efficiently absorbing enough CO2.
If you don’t have fans or air circulation actively moving CO2-rich air around your plants, they’ll never be able to absorb enough CO2 to boost their growth regardless of how much CO2 you are pumping in there.
At the same time, they absorb CO2 through the stomata, and leaves are also regulating water loss via transpiration. They open and close stomata to reduce water loss. So, while these stomata are closed, they aren’t absorbing CO2.
Studies have shown that when the CO2 concentrations are raised above ambient levels, the plants respond by shutting down the stomata. Without the need to absorb extra CO2, plants move into water conservation. This means that water per plant may decrease with additional CO2 fertilization and makes air mixing very important.
Ideal CO2 Levels for Growing Plant
The most debated part of CO2 fertilization is how much is too much and what’s the right concentration? Unfortunately, there isn’t a lot of research, but some research suggests that levels above 700 ppm resulted in a positive, almost instant increase in photosynthetic productivity.
Tomatoes can tolerate up to approximately 2,000 ppm, and some other indoor-grown commercial plants top out at around 1,600 ppm. The best recommendation from most growers is not to exceed 800 ppm during the vegetative phase. It will provide a nice boost before the plants move into their flowering stage.
During the bloom or flowering stage, 1,200-1,600 ppm is a good range but don’t exceed 1,600 ppm. Hopefully, as the plant industry continues to grow and we see more people enter the market, research and studies into CO2 and plant are expanded to provide us with more accurate information.
Ideal CO2 Levels for Growing Plant – Conclusion
Hopefully, now you have a much clearer idea of how to incorporate CO2 into your grow operation and the benefits associated with it. While CO2 isn’t going to be for everyone, it can be a positive and beneficial addition to any grow setup or for growers looking to achieve maximum yield and quality on their harvest.
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8 thoughts on “Ideal CO2 Levels for Growing Plant”
Hey all , what one would be suffient for my 4′ x 8′ grow tent ? Thank you , Lindsay
Hi friend, we recommend 2 SE5000 or 2 SF4000 for 4’x8′ tent
The above article says parts per million, so it doesn’t matter how big or small your tent is, you could do with a CO2 monitor that tells you precisely how many ppm of CO2 you are getting.
i want to try it sometime
I’ve seen independent research claiming being in your tent for 1 hour a day will raise c02 high enough for our needs in small operations. Interesting to see where research brings us on this in the future.
I got a 100′ roll of blue cellophane. I put the blue cellophane under my led light like a tent, the closer the better coverage. It greatly increase the leaves. A regular 100 white bulb over the blue cellophane works perfect. Also, in winter when the sun gets low in the sky covering a window keeps all’ plants thriving. I use blue cellophane and tilted reflectors at different heights (4-sides) to reflect light into the plant.
for 15 years I’ve been using blue cellophane and reflectors on all 4-sides (reflector w/blue foil on pizza box, I prefer). Also, in winter I cover the south window with the blue cellophane. The plants thrive and leaf output increases immensely (X’s 10). Just blue cellophane i.e. blue in the spectrum. Otherwise I put the blue cellophane between the a light and the plant. I believe in Blue and Red Cellophane (used for wrapping baskets, clear too).