Even the balmiest of growing regions can be subject to the occasional frost during the winter months. Damage to tropical plants can be minor or extensive, affecting all parts of the plant including leaves, fruit, bark and roots. Signs of frost or freeze damage includes plant tissue death, cracked bark and darkened, mushy stems. If the roots of certain tropical plants freeze, the plant will die. Proper plant selection and a program of regular care will improve overall survival rates, but emergency measures may be needed if temperatures drop unusually low.
Consolidate potted plants. Container grown plants are vulnerable to root injury if temperatures plunge. If possible, push container plants into a group and cover them with mulch, hay or a blanket. If the pots are too large to move, wrap the containers in burlap or plastic to minimize heat loss.
Mulch taller, in-ground plants. Heat radiates from the ground to protect low-growing plants, but taller plants do not have that advantage. Mulching helps to regulate ground temperatures and provides some extra heat to plants. Some tropical plants may be killed by a hard frost, but mulch will protect the roots and the plants will survive until the following spring.
Cover plants with burlap, lightweight blankets, bedsheets or cardboard boxes. This prevents cold injury to leaves while allowing the plants to breathe. Remove the coverings during the daytime.
Water plants when a freeze is expected. According to the University of Georgia Cooperative Extension, moist soil absorbs more heat and keeps the temperatures around your plants higher.
Sprinkle plants with water during a freeze. According to the University of Florida Extension, this technique "helps keep leaf surface temperatures near 32 degrees F (0 degrees C) because sprinkling utilizes latent heat released when water changes from a liquid to a solid state."
Begin sprinkling as soon as temperatures begin to fall and continue until temperatures rise. Because you must maintain a film of water on the leaf surfaces at all times, an automatic sprinkler will be necessary.