On Earth, all plant life thrives abundantly in an atmosphere rich in CO2 (carbon dioxide or carbonic gas) and O2 (oxygen). Without these conditions, life would be impossible! Through the stomata covering their leaves (similar to human pores), plants release oxygen (while also consuming it, but to a lesser extent) and assimilate CO2 (while also releasing some, but in smaller quantities).
Given this fact, recreating outdoor climate conditions as closely as possible indoors ensures bountiful and speedy harvests.
Plant Growth and Carbon Dioxide
Plants produce their own organic matter (sugar, cellulose, energy) from water and CO2, which is assimilated by the leaves through the process of photosynthesis, powered by solar energy. Without this gas, the plant cannot survive. Through the stomata on their leaves, plants release more oxygen than they consume and absorb much more CO2 than they emit. In indoor environments, none of the natural elements that generate CO2 are present, except for the plant itself. It is the responsibility of the horticulturist to provide the plant with the necessary carbon dioxide.