If you live in Southern AZ, you are very aware that we have had some very cold nights that were well below freezing. Many of your plants have been damaged by the cold so, it is good to know how to deal with plants in cold weather or when cold snaps are suspected.
Protect Plants from Cold Weather
Of course, the ideal step is to protect plants from getting damaged from cold weather at the onset. Freeze damage occurs when the water held within the cells of plant tissue freezes causing damage to cell walls and dehydration. Such damage can be prevented on many plants by taking a few precautionary measures.
Tender plants, shrubs and small trees can be covered with a frost blanket or burlap sacks. These provide a barrier that absorbs the frost and keeps it from damaging the covered plants. However, such protection should be removed when the sun is shining as this is dangerous for plants as well. Any potted plants should be taken into a sheltered area such as indoors or a fully covered garage.
Saving Cold Damaged Plants
If a cold snap does catch you by surprise and plants are damaged from frost or freezing weather, there are some things you can do to save them.
If potted plants are left outside and receive cold damage, you can take them inside, allow them to heat up, and prune damaged leaves or branches. However, if the plants are based in the ground outside, do not prune any damage right away. Wait until warm weather returns and new growth begins before attempting to prune such damaged plants. Damaged foliage and/or branches provide protection to living tissue in the case that more cold weather hits. Some of the common plants that fall in this category are Lantana, Bougainvillea, Mexican Red Bird of Paradise, Dwarf Oleander, Yellow Bells and Salvia.
Pruning Guidelines
When the weather has warmed sufficiently and new growth begins to appear, you can successfully prune away any damage. A general rule is to wait until April 1st to cut back damaged foliage. I like to start pruning the damages foliage back until you hit green wood. In some cases this is all the way to the ground.
If you are pruning cacti, care should be taken due to their harsh reaction to wrongful pruning and ease at acquiring infections. When pruning a cactus, only prune areas which have been damaged by frost. Pruning should be at joints and powdered sulfur should be applied to cut areas so that they dry out rapidly and don’t contract infections. Give your plants until the end of April to show signs of recovery. If you see no signs by April 30th they may need to be replaced.