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Growers’ Circle

Supplemental CO? can help optimize growth

By Dr. Who

Humans breathe in oxygen (O?) and breathe out carbon dioxide (CO?). Plants do the reverse. They “breathe in” CO? and




Supplemental CO? can help optimize growth

By Dr. Who

Humans breathe in oxygen (O?) and breathe out carbon dioxide (CO?). Plants do the reverse. They “breathe in” CO? and “breathe out” oxygen (O?). This is why plant life is an essential part of the worlds’ ecosystem. Without plants, CO? levels would rise to intolerable levels. Plants use CO? for growth. It is the essential building block for photosynthesis (along with light and water). Plants cannot grow without CO?. The current levels in the atmosphere are about 350 parts per million (PPM). It is theorized that millions of years ago, levels of CO? were about 1,500 PPM. Throughout the years, plants have evolved in many ways—and in many ways have stayed the same. Knowing this can be advantageous for us all.

It seems that plants have not lost the ability to use up to 1,500 PPM of CO?. Plant growth can be accelerated by increasing the CO? levels in your growing area. Conversely, CO? levels below 250 PPM have a detrimental effect on your plants. If you have six plants growing in your closet, and there is no ventilation, your plants can use the CO? in a few hours. They then stop growing. You must, at a minimum, provide fresh air for your plants every hour or so. An even better way is to provide supplemental CO? for your plants by using either a CO? generator or bottled CO?. Any of these solutions will keep your plants growing at optimal rates. It has been proven that you can increase your growth rates by up to 20 percent and size by up to 30 percent by providing supplemental CO? at levels over 1,200 PPM. You should never go over 1,500 PPM, as this soon becomes toxic for the plants, and they tend to grow very stringy.

CO? generators are simply specialized burners that burn either propane or natural gas to produce CO?. A byproduct of this process is water, in the form of humidity. When using a generator, it is a good idea to keep an eye on your humidity levels. CO? generators are optimized to produce as little heat as possible, while producing as much CO? as possible. They are normally rated in cubic feet per hour (CFH). A standard 10-foot-by-10-foot-by-8-foot room containing 350 PPM takes about 1 CFH to raise the levels to 1,500 PPM. The level will drop throughout the day, requiring smaller burns to keep the levels constant. A CO? PPM controller works great for keeping your levels constant with a CO? generator.

Bottled CO? can be obtained at most hydroponic or welding stores. You need a regulator/flow meter to get the CO? out of the bottle in a measured manner. You set the flow rate in CFH and set the regulator on a timer to bring your CO? levels to the desired level. A few calculations will be needed to set your CO? levels correctly. You can also use a CO? PPM controller to maintain your levels.

Plants do not use CO? at night. It is not necessary to supplement CO? during your dark cycles (mushrooms are an exception). Properly used, supplemental CO? will only help your crops if you have all of your other factors in line, such as using a good nutrient mixed at an appropriate strength, changing your nutrients to prevent nutrient deficiencies, having enough (and not too much light) and keeping your temperature and humidity are also plant limiting factors. Once you have dialed in all these, supplemental CO? can help you gain the most return on your plant growth.

DR. WHO is a Southern California expert in plant cultivation. Reach him at