One of the main variables associated with indoor vegetable gardening is the manipulation and control of lighting. Today, we look at the science behind lighting and what exactly indoor grow light systems achieve.


Outdoor gardening is pretty self-sufficient in terms of regulating the flow of air and light. There’€™s not much you can do to adjust wind and sun; however, hydroponic gardeners have to provide air and water flow, as well as the intensity and interval of light. Without this, photosynthesis will not occur. Photosynthesis is as important to a plant as digestion is to a human.

Photosynthesis begins when the right kind of light hits the green pigment in the plant’s leaves called chlorophyll. When the light interacts with the chlorophyll, it mixes with carbon dioxide and water to make oxygen and sugar. The sugar is oxidized through a process called respiration, which turns carbon dioxide and water into energy. Other micro-nutrients present inside the growing medium are absorbed by the root system, contributing to the strength of the plant. The by-product of photosynthesis is oxygen, which the plant releases into the atmosphere. The fact that humans require oxygen to survive makes the human-plant relationship truly symbiotic.

When the plant respirates, it emits carbon dioxide and water. Tiny openings on the underside of the leaf – called stomata – absorb carbon dioxide and emit oxygen during photsynthesis, while the inverse is true during respiration. Because carbon dioxide exists in the atmosphere in very small quantities, the stomata are wide open during the hours that the leaves are absorbing light (photosynthesis). If the humidity is too low, this can cause evaporation of the plant’s moisture. The root system needs extra water to compensate for this. If water is sparse, the leaves will suffer and look wilted. This is called transpiration. To avoid transpiration, hydroponic systems need an atmosphere that is humid enough for the plant to achieve a balance between respiration and photosynthesis.

Sounds complicated? It isn’t, really. As long as you have a room thermometer and a hydrometer to track the heat/humidity levels in the air, you can keep the environment in the range for your type of vegetation and the plant will do the rest of the work.