Even in areas that are generally warm, there is sometimes a danger of frost, which can wreak havoc on your trees and other plants. Some plants are more resistant to frost than others, but some plants won't survive at all if they are not covered during a hard freeze--including many fruit trees. You can bring potted trees and shrubs indoors until the danger has passed, but you will need to protect your outdoor trees by providing a barrier between the tree and the frost. Blankets, layers of plastic, cardboard boxes and mulch can all be used to protect fruit trees in a hard freeze.
Add a thick layer of mulch around your fruit trees to protect their roots. This acts in much the same way as a blanket, by providing an insulating layer that holds in the heat in the ground.
Use cardboard boxes to cover smaller trees and shrubs. The boxes provide insulation and work like a small greenhouse.
Cover the trunks and larger branches with black roofing paper to provide a protective barrier.
Cover larger trees with plastic. Build a temporary frame for the plastic if you have an area with several trees, then wrap the frame in plastic or attach it with staples. For added protection, cover the tree or shrub with a blanket first, then plastic. Anchor the blanket and plastic in place with stones or bricks.