What is green house? Discuss about the different methods of construction of green house.

 Greenhouse is an enclosure where proper environment is provided for growth and production of crops, vegetable and flower plants under adverse climatic conditions. By controlling the environment a particular vegetable or flower can be grown throughout the year. The design of a greenhouse depends on local climatic conditions. In cold countries, winter greenhouse provide supplementary heat to maintain adequate temperature during cold months when solar insolation is low. In tropical countries, the solar insolation and ambinet temperatures are quite high and therefore summer greenhouse are used to maintain low temperatures inside and allow just sufficient sunlight for photosynthesis. Greenhouse for arid zone are designed to conserve water resources. Although there is slight variation in the environmental needs of each variety of plants for best production, basically they all require moderate temperatures and light, adequate quantities of carbon dioxide, oxygen, mineral nutrients, air movement and water, as indicated in the table below. Moderate temperatures, light and air movement are energy related needs of plants and supplied by the greenhouse. A greenhouse designed to use solar energy to meet these requirements is known as solar greenhouse. If natural means are adopted to collect store and distribute the energy inside, it is known as passive greenhouse. A greenhouse where auxiliary means are used for these functions is known to be an active one. Generally a combination of both active and passive features is employed in solar greenhouse to minimize the need of auxiliary energy.

Five Basic Types: Following are some types of greenhouse conceived with specific uses in mind. Each is accompanied by a list of items required for optimal use of such a structure.

1. The Tropical Greenhouse : A tropical greenhouse is likely the most expensive type to heat during a cold northern winter. If you are going to heat your greenhouse to the levels required by tropical plants, you can install double or even triple pane glass or polycarbonate and accept the slight loss of light caused by the additional glazing. Light levels in such a greenhouse are typically about 70 to 90 percent of those outdoors. Plant leaves tend to burn if they are placed in direct sunlight after being in such an environment for months.

2. The Warm Greenhouse: Some tropical plants can be grown in a warm greenhouse. Warm greenhouse must be heated at night during northern winters. Heaters can be fulled by propane, natural gas, electricity, or even wood. A wood burning stove, however, emits dry heat that is not beneficial to plants.

3. The Orchid Greenhouse: Various orchid species require specific growing conditions including unique light and temperature. To specialize in growing orchids in a greenhouse one should know a fair amount about orchid growing so that greenhouse structure and systems can match these special requirements.

4.The Cool Greenhouse: Most leafy green vegetables can stand much lower temperature than orchids and grow best between 50°F and 70°F and many vegetables will survive almost to freezing. A freestanding greenhouse without a heating system will allow vegetable to grow for most of the year and will enable them to survive for most of the winter in areas up to Zone 5 or 6.

5. The Alpine Greenhouse: Like many plants associated with specific climates or locations alpine plants require unique conditions to survive those that re create the conditions found at high altitudes, where the plants are covered with frozen snow or ice for much of the year and bloom in the short, high altitude summer.