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Polytunnels on Balhungie Farm, Angus
A polytunnel (also known as a polyhouse, hoop greenhouse or hoophouse, grow tunnel or high tunnel) is a tunnel typically made from steel and covered in polyethylene, usually semi-circular, square or elongated in shape. The interior heats up because incoming solar radiation from the sun warms plants, soil, and other things inside the building faster than heat can escape the structure. Air warmed by the heat from hot interior surfaces is retained in the building by the roof and wall. Temperature, humidity and ventilation can be controlled by equipment fixed in the polytunnel or by manual opening and closing of vents. Polytunnels are mainly used in temperate regions in similar ways to glass greenhouses and row covers. Besides the passive solar heating that every polytunnel provides, every variation of auxiliary heating (from hothouse heating through minimal heating to unheated houses) is represented in current practice. The nesting of row covers and low tunnels inside high tunnels is also common.[1]
Superbay Polytunnel at Van Arnham Nurseries
Polytunnels can be used to provide a higher temperature and/or humidity than that which is available in the environment but can also protect crops from intense heat, bright sunlight, winds, hailstones, and cold waves. This allows fruits and vegetables to be grown at times usually considered off season; market gardeners commonly use polytunnels for season extension.[2] Beyond season extension, polytunnels are also used to allow cold-hardy crops to overwinter in regions where their hardiness is not quite strong enough for them to survive outdoors. Temperature increases of only 5 to 15 °C (9 to 27 °F) above outdoor ambient, coupled with protection from the drying effect of wind, are enough to let selected plant varieties grow slowly but healthily instead of dying. The effect is to create a microclimate that simulates the temperatures of a location several hardiness zones closer to the equator (and protects from wind as well).
Superbay Polytunnel - Otter Nurseries
Every factor influencing a crop can be controlled in a polytunnel. Polytunnels are often used in floriculture and plant nurseries, as the revenue value of the plants can justify the expense.
In recent years the true adaptability of polytunnel structures has been realised by adapting them to suit livestock housing. It is now commonplace in the UK to see polytunnels used for housing sheep, alpacas, goats, calves and poultry.
^Blomgren, Ted; Frisch, Tracy (May 2007). "High Tunnels: Using Low-Cost Technology to Increase Yields, Improve Quality and Extend the Season" (PDF). SARE (Sustainable Agriculture Research and Education). Retrieved 26 October 2020.
^"Winter Production in the High Tunnel | Johnny's Winter Growing Guide". www.johnnyseeds.com. Retrieved 26 October 2020.
A polytunnel (also known as a polyhouse, hoop greenhouse or hoophouse, grow tunnel or high tunnel) is a tunnel typically made from steel and covered in...
English. The polytunnels have been a major issue in the county, as some people see them as a "blot on the landscape". Although some polytunnel sites are...
neighbour to rent four acres (≃16,200 m2). His smallholding now boasted a polytunnel for growing vegetables, a fox-proof high rise chicken accommodation and...
including Ray Smith (a freelance butcher) and Michael Michaud an organic polytunnel expert. [citation needed] In September 2006 River Cottage HQ moved to...
an undercover walk-through in a sustainably-heated, climate-controlled polytunnel. [1]. Species on show included the blue morpho butterflies, glasswings...
extend the harvest throughout the winter, mostly through the use of polytunnels. Starchy root vegetables are of particular economic importance as staple...
Plastic transparent materials have also been used to similar effect in polytunnels and row covers. Development of a solar-powered car has been an engineering...
season can be lengthened by the use of fleece, cloches, plastic mulch, polytunnels, and greenhouses. In hotter regions, the production of vegetables is...
conditions (for which he uses unheated and minimally heated greenhouses and polytunnels). He even manages to grow artichokes, claiming that "I grow them just...
ornamental crops. It is frequently found in glasshouses (greenhouses), polytunnels, and other protected horticultural environments. Adults are 1–2 mm in...
rest 98% is for cooling purpose through transpiration. Shade nets or polytunnels installed over the agricultural lands suitable for all weather conditions...
range from plastic mulch film, row coverings, high and low tunnels (polytunnels), to plastic greenhouses. Plastic used in agriculture was expected to...
dove Ring-tailed lemur Red ruffed lemur Alaotran gentle lemur A large polytunnel was built with used tyres in spring 2011. It is the new home of two species...
planting a plant in a pot, such as a flowerpot Sowing in greenhouses or polytunnels is often done in pots, pending later transplant Potting soil is a type...
a gently undulating agricultural landscape of arable/pasture fields, polytunnels associated with fruit farms and woodland cover associated with hill slopes...
continue into late autumn by growing cold-resistant cultivars under heated polytunnels. Furthermore, late season harvests can be achieved using 'reverse season...
via aeroplankton. Significant protection against this is afforded by polytunnels. Daugovish & Larson 2009 find 84%–90% greater yield and 62%–140% greater...
range from plastic mulch film, row coverings, high and low tunnels (polytunnels), to plastic greenhouses. Plastic used in agriculture was expected to...
Emirates. The design is a light steel structure, similar to a multi-span polytunnel, which relies purely on solar energy. A pipe array is installed to improve...
transplanting are grown. For seedling starting in commercial greenhouses or polytunnels, pots usually take the form of trays with cells, each cell acting as...
goats, are sometimes raised specifically for their hides. high tunnel See polytunnel. high-yielding variety (HYV) hill farming A type of extensive agriculture...
discovered that pensioner Lily Butterfield (Anne Charleston) was using her polytunnel to grow cannabis to help with her arthritis. He began to blackmail her...
Fruit-growing polytunnels with caravans for the mainly Eastern European fruit workers conveniently parked behind, Perth and Kinross, Scotland, March 2009...
of warming in a similar way to unheated cold frames, greenhouses and polytunnels, creating a microclimate for the plants. The first commercial-scale use...
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