A greenhouse, glasshouse or hothouse is a building where plants are cultivated. A greenhouse is a building or structure that has a glass or plastic roof and walls. They heat up because incoming solar radiation from the sun warms plants, soil, and other things inside the building.
Greenhouses range in size from large multi-sectioned buildings or complexes to the small shed-like structure.
Uses
Greenhouses are often used for growing flowers, vegetables, fruits, and specialty plants where exposure to the outdoors would limit or prevent growth.
For gardeners, 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 or commercial greenhouses or garden centres at transplanting time.
Greenhouses are increasingly important in the food supply of high latitude countries. The largest greenhouse complex in the world is in Willcox, Arizona, USA where 262 acres of tomatoes and cucumbers are entirely grown under glass (Wikipedia). A large community greenhouse in Inuvik, which, at 200 kilometres above the Arctic Circle, is thought to be the world's most northerly commercial operation and Canada's only community hothouse.
History
The first modern greenhouses were built in Italy to house exotic plants that explorers brought back from the tropics. They were originally called giardini botanici (botanical gardens). This concept spread throughout Europe, along with the plants. Some of these early attempts required enormous amounts of work to close up at night or to winterize. There were serious problems with providing adequate and balanced heat in these early greenhouses.
Originally on the estates of the rich, with the growth of the science of botany greenhouses spread to the universities. The British some times called their greenhouses conservatories, since they conserved the plants. The French called their first greenhouses orangeries, since they were used to protect orange trees from freezing. As pineapples became popular pineries were built.
Mother Nature's Greenhouse
Nurseries use mother nature's greenhouse to grow plants for, typically, retail sale to the general public. Nurseries may also be larger operations supplying the needs of commercial landscapers, institutions or municipalities. Plants grown in nurseries are typically propogated from seedlings to more mature plants that are hardy enough to be transplanted.