Carbon Dioxide and Better Indoor Harvests


            Part II: Supplement with CO2 during the day-


With carbon comprising as much as 40% of the plant material in harvest yields, CO2 is a major plant nutrient that significantly drives plants’ growth rate, development, and ultimately, yield. Along with the light and water required for photosynthesis, carbon dioxide creates sugars that further drive growth and development.

As plants absorb carbon dioxide during the day, they release oxygen as a byproduct into the environment. (This process reverses at night, and plants “exhale” carbon dioxide just as animals and humans do, and absorb oxygen.)

Why it’s important to enrich your grow room with extra CO2 during the day

• To prevent CO2 depletion

Atmospheric carbon dioxide is about 300-360 parts per million (ppm), but indoor plants with fast growth and adequate light thrive on about 1200 ppm. Plants will use the naturally available CO2 up very quickly, and if they’re not supplied with more, growth and development stops. Bringing the CO2 level up to about 1200 ppm and then maintaining that during the day gives plants the energy they need to produce optimum yields.

• To boost growth

CO2 enrichment during the day can boost plant growth and yields by 20 to 40%.

• To kill off pests

If your grow room is completely sealed, increasing CO2 to 10,000 ppm for an hour can kill pests. (Caution: Growrooms must be *completely* sealed to prevent human CO2 overexposure and potential health problems.)


• Make sure all other elements are in balance

While most plants will thrive with CO2 supplementation during the day, temperature, water and light must also be supplied at the proper levels for good results.

You can have too much carbon dioxide

Even though plants need CO2, too much can be harmful. Plants that take in too much carbon dioxide can deteriorate when pushed to the limit during flowering cycles, and can produce fewer and smaller buds if this happens.

• DON’T supplement with CO2 at night

At night, the photosynthesis process ceases and respiration begins. In respiration, plants exhale carbon dioxide and inhale oxygen. Supplementing with CO2 is unnecessary and may actually stunt plant growth.

More on respiration and its importance to plant growth, next time.