Garden & Greenhouse


Making the Most of Your Garden by Understanding CO2

Posted August 6th, 2008 by Angela Lundmark in

pepper14The number one limiting factor in efficient photosynthesis is Carbon Dioxide. What this means is although plants need light, nutrients, and water, it is the make-up of our air that is holding the majority of plants back from reaching their full potential. For centuries we have grown our plants in fields where we had little choice but to accept the level of CO2 in the air. By placing compost around the plants we were able to reap some of the benefits of enhancing CO2 concentrations but there was no way to trap the CO2. As more and more growers choose to grow in greenhouses and indoors where it is easier to manipulate and control their environment, it has become more practical to utilize CO2 to help plants reach their full potential.

Plants need CO2 much in the same way that we need oxygen. They cannot live without it.  We can keep ambient levels through proper ventilation but plants are able to utilize much more than nature provides. The average air we breathe is 300-400 ppm. Plants will stop growing at 150 ppm. In a closed growing environment this level is quickly reached as the concentration is constantly being depleted by the process of photosynthesis. Researchers studying the effects of CO2 on plants have found that under otherwise optimal conditions –  we can gain a 40% increase in yield by simply raising the CO2 level to 700-1600 ppm.

So how do you do it? There are CO2 sensor kits that range from $20 and up to gauge the concentration of CO2 in a room. It is important to know the CO2 levels before you start adjusting them. Levels of 20,000 ppm will make us pass out and 2500 ppm can give you headaches. Ventilation should protect against these levels but better safe than sorry. The most common method of boosting CO2 you are already doing if you spend time with your plants. Our breath contains 35,000 to 50,000 ppm of CO2.

Two affordable methods that would be appropriate for small areas include keeping composting material in a bucket with a gas release valve or creating CO2 by mixing sugar, water, and yeast. To get the most of these methods you will want to be sure that you have a low level oscillating fan to circulate the CO2 which has a tendency to float to the ground. The ideal methods will require an investment. A CO2 injector utilizes a basic CO2 tank that you fit with a regulator to adjust flow. The basic system will cost around $150 and you will need to replace the tank periodically. A CO2 generator generally runs off of propane and can run anywhere from $450 to $1,600. The upscale versions will monitor the CO2 concentrations and turn themselves on or off when levels are in the range you have selected.

We learn about the Carbon Cycle in Elementary school so when I talk to clients I’ve found that the topic of CO2 often gets washed into the “yeah, yeah, I know” category. But what many people don’t know is that extra lighting and nutrients provided to your indoor garden may be going to waste without it. Plants use the light energy to combine Carbon Dioxide and water which it turns to sugars that form carbohydrates that mix with the nutrients in order to increase biomass. This means that you can pump your garden full of light, water, and nutrients but if the CO2 isn’t available to put this process into motion- the plant cannot use it. The moral – make sure you are making the most of the equipment and supplies you purchase by supplementing CO2. Your plants won’t grow without it.

Angela Lundmark, CEO of LED Grow Master Global

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