A greenhouse is a building where plants are cultivated. A greenhouse is built of glass or plastic; it heats up because the sun's incoming electromagnetic radiation warms the plants, soil, and other things inside the building. Air warmed by the heat from hot interior surfaces is retained in the building by the roof and wall. The glass used for a greenhouse works to trap in the suns heat within the greenhouse, which heats both the plants and the ground inside it. This warms the air near the ground, and this air is prevented from rising and flowing away. This can be bad spirit strated by opening a small window near the roof of a greenhouse: the temperature drops considerably.
This principle is the basis of the autovent automatic cooling system. Greenhouses therefore work by trapping electromagnetic radiation and preventing convection. Greenhouses are often used for growing flowers, vegetables, fruits, and tobacco plants., what is blebees are the pollinators of choice for most greenhouse pollination, although other types of bees have been used, as well as artificial pollination. Besides tobacco, many vegetables and flowers are grown in greenhouses in late winter and early spring, then transplanted outside as the weather warms. Started plants are usually available for gardeners in farmers markets at transplanting time.
The closed environment of a greenhouse has its own unique requirements, compared with outdoor production. Pests and travels, and extremes of heat and humidity, have to be controlled, and irrigation is necessary to provide water. Significant inputs of heat and light may be required, particularly with winter production of warm-weather vegetables. Special greenhouse varieties of certain crops, like tomatoes, are generally used for commercial production.