A greenhouse is used to shield plants from the environment, particularly the cold. Using clear materials such as glass or plastic for the roof and walls, greenhouses use the radiant energy of the sun to keep plants warm. For many years greenhouses were made primarily of glass, but as the development of plastics has progressed, more gardeners began taking advantage of the lighter weight, less expensive building material. As a result, many modern greenhouses are made of plastic sheets and films. While these films are durable, they do occasionally tear. Luckily, this type of damage is easy to repair.
Use a measuring tape to determine the size of the tear. Record the measurements, being sure to note both the length and width as you will be using them to establish the patch size.
Obtain a piece of polyethylene sheeting large enough to patch the tear. Polyethylene sheeting can be found at home improvement stores, garden centers and the hardware section of major department stores.
Use your measurements to determine the size of patch you will need and then cut two patches from the sheet with a utility knife. Make sure the patches are at least ¼ inch larger than the tear in both length and width.
Combine one tablespoon of liquid soap with one quart of water. Use the soap solution to wash the damaged area of the greenhouse plastic. Pat the area dry with a paper towel. The surface needs to be clean and dry on both sides for the adhesive to stick.
Position one of the patches so that it completely covers the tear and tack it in place with strips of packing tape. Cover the patch with pieces of tape, working from the top to the bottom and placing each strip of adhesive so that it slightly overlaps the edge of the one that came before it.
Repeat the patching procedure on the opposite side of the film, pressing any air bubbles out from between the patches as you work.