Vegetables growing inside a small garden greenhouse. (Source: © dbrus / stock.adobe.com)

A structure with large transparent areas, inside which a different temperature and humidity than outside can be maintained, and where off-season vegetables, fruits or tropical plants can be grown. Greenhouses can have a variety of support frames (metal, concrete, plastic etc.) with glass or plastic windows. Sunlight penetrating through the windows warms the interior of the greenhouse. Because warm air cannot escape from the closed greenhouse and infrared radiation cannot pass through the glass, the inside of the greenhouse becomes hotter than outside. This makes it possible to grow heat-loving plants. Greenhouses are usually also equipped with irrigation, ventilation, lighting, heating and/or cooling. Most of the vegetables and fruit we buy in winter are grown in greenhouses.