Greenhouse crop production was a very significant event in the history of agriculture since it was realized that with the help of it many plants could be protected from different biotic and abiotic stress. It emerged as a system to protect crops from critical and adverse conditions affecting the growth of plants. The greenhouse is a non-linear system and controlling becomes a difficult task. The parameters affecting the plant growth are temperature, relative humidity, carbon dioxide, nutrition, availability of water and the growing media. The quality and productivity of the crop plants is highly dependent on the management of these parameters. From all the parameters, temperature and humidity are of primary importance to most growers as it is responsible for determining the reaction rates of various metabolic processes involved in the plant growth. In addition, regulating temperature has a direct influence on the relative humidity and carbon dioxide levels of the greenhouse system.