It has long been known that the green part of plants, when exposed to light under suitable conditions of temperature and water supply, intake carbon dioxide from the atmosphere and release oxygen into it. This gaseous exchange is the result of photosynthesis. The intensity, quality and daily duration of illumination all influence the amount of photosynthesis that takes place.

Each type of plant, whether it's sun-loving or shade-tolerant, has its own rate of photosynthesis. More photosynthesis appears to occur in the orange, short red and blue bands of the spectrum than in the green and yellow bands. In general, the longer the daily amount of illumination, the more photosynthesis will take place.