Greenhouse

.]] A greenhouse (or glasshouse) 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 (particularly infrared light) warms 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 acts as a selective transmission medium for different spectral frequencies, and its effect is to trap energy 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 demonstrated by opening a small window near the roof of a greenhouse: the temperature drops considerably. Greenhouses thus work by trapping electromagnetic radiation and preventing convection.

Greenhouses are often used for growing flowers, vegetables, fruits, and tobacco plants. Bumblebees are the pollinators of choice for most greenhouse pollination, although other types of bees have been used, as well as artificial pollination.

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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.

Greenhouses are increasingly important in the food supply of high latitude countries. The largest greenhouse complex in the world is at Leamington, Ontario (close to Canada's most southern spot)where about 200 acres of tomatoes are entirely grown under glass.

See also

• Greenhouse effect

External links

• North Carolina State University Greenhouse Food Production website
• Organic Greenhouse Tomato Production}