A greenhouse can protect plants and vegetables from the cold, making it possible to grow them year-round. Greenhouses are made from clear glass or plastic to allow radiant energy from the sun to enter and keep plants warm. Plastic is lighter than glass and is durable, but it can occasionally tear and will need to be repaired in order to keep cold air out and maintain a consistent temperature inside the greenhouse.
The first step in repairing the plastic in your greenhouse is to measure the size of the torn piece. Note both the length and the width of the tear.
Once you know how big the tear is, you will need to purchase a piece of polyethylene large enough to cover it. You can buy polyethylene sheeting at a home improvement store, garden center, or hardware section in a department store.
Use a utility knife to cut two patches from the sheet of polyethylene. They should be ¼ inch larger than the hole in terms of both length and width.
Mix one tablespoon of liquid soap and one quart of water. Wash the damaged area of the greenhouse plastic and then pat the area with a paper towel to dry it. The surface must be clean and dry on both sides for the adhesive to stick.
Use one patch to completely cover the tear and then use strips of packing tape to secure it in place. Cover the patch with pieces of tape. Work from top to bottom and place them so each piece of tape slightly overlaps the one before it. Repeat on the other side of the film and press any air bubbles out from between the patches.