
Greenhouse Carbon Dioxide Supplementation - Oklahoma State University
By Megha Poudel and Bruce Dunn. Learn about carbon dioxide, its concentration in relation to plants, supplementation, the effect of supplemental CO2 on different growing factors, sources of carbon dioxide and control and distribution of CO2.

The carbon dioxide level may drop to 150 to 200 parts per million during the day in a sealed greenhouse, because CO2 is utilized by plants for photosynthesis during daytime. Exposure of plants to lower levels of CO2 even for a short period can reduce rate of photosynthesis and plant growth.
Interesting reading on why they enrich co2 levels to 1,000ppm in greenhouses. Above 1,800ppm, they think it may cause plant damage. As plants are categorised, it's likely tomatoes and cucumbers that might get upset. So eat more meat!!
If you're thinking of using a greenhouse, give it a read, you might want to use extra co2.