Let us start with a basic explanation of what plants do with light. Plants absorb light energy using chlorophyll in their leaves. They use this energy to cause a reaction between water and carbon dioxide that produces a sugar called glucose. This is the main food source for the plant; it is either used, or stored within the plant as starch. This process is called photosynthesis.

It should be noted that light intensity, ambient temperature and the level of carbon dioxide in the air, all play a part on how efficiently a plant photosynthesizes. This is why it is so important to maintain a grow room at optimum levels; without these your plants will not grow to their full potential.