Polytunnels

A polyhouse, hoop greenhouse, hoophouse, grow tunnel or high tunnel is warmed up by solar radiation and the heat is retained so that fruit and vegetable food crops can be grown at times usually considered off season, for season extension as cold frames and both smaller plants and trees can overwinter in cold regions. Hoophouses are used in similar ways as greenhouses and cloche row covers and can be made as low tunnels or high tunnels and permanent or moveable. Polytunnels provide a higher temperature and humidity than the immediate outside environment but can also protect crops from intense heat and bright sunlight in hot climates, winds, hailstones, cold waves, frost and protection from the drying effect of wind. Besides commercial food production farming, polyhouses are used in floriculture and nurseries to protect cut flowers and young plants and for livestock housing in animal husbandry.
Every variation of auxiliary heating, from hothouse heating through minimal heating to unheated houses may be employed along with the control of temperature, humidity and ventilation by manual opening and closing of vents or completely automated with climate control equipment to provide microclimates.