A cover to protect plants, such as rosebushes, azaleas, rhododendrons and the like, against winterkill and to maintain the plants in a dormant state is provided in the form of a multilayer bag with an air space between the layers, skirts or flaps at the mouth of the bag adapted to be covered with earth...http://www.google.com.au/patents/US4646467?utm_source=gb-gplus-sharePatent US4646467 - Weather resistant cover bag for dormant plants
