Biologists and plant physiologists have long recognized the benefits of higher CO2 content in the air for plant growth. Horticulturists and greenhouse growers have used CO2 generators to enhance growth rates on plants for many years with good results.
With the advent of home greenhouses and indoor growing under artificial lights and the developments in hydroponics in recent years, the need for CO2 generation has drastically increased. Plants growing in a sealed greenhouse or indoor grow room will often deplete the available CO2 and stop growing. The following graph will show what depletion and enrichment does to plant growth:
(see chart above)
Below 200 PPM, plants do not have enough CO2 to carry on the photosynthesis process and essentially stop growing. Because 300 – 395 PPM is the atmospheric CO2 content, this amount is chosen as the 100% growth point. You can see from the chart that increased CO2 can double or more the growth rate on most normal plants. Above 2,000 PPM, CO2 starts to become toxic to plants and above 4,000 PPM it becomes toxic to people.
With the advent of ideal growing conditions conditions provided by metal high-intensity discharge (H.I.D.) lighting systems, hydroponics, environmental controls such as temp., humidity, etc. and complete, balanced plant nutrients. The limiting factor on plant growth rate, quality, size and time to maturity becomes the amount of carbon dioxide available to the plants.