Polytunnel
A tunnel of plastic sheet stretched over hoops, used as a cheap, simple greenhouse.
Also: hoop house, high tunnel, polyhouse
A polytunnel is a row of metal hoops covered with clear polythene. It costs far less than glass and can be put up quickly. It keeps off rain and wind and adds warmth, which lengthens the season and gives cleaner, longer stems. Small flower farms use tunnels for crops such as ranunculus, anemones, lisianthus and early dahlias. In India the same kind of structure is usually called a polyhouse and is widely used for roses, gerberas and carnations.