With freeze warnings in effect over the next week, you can do several things to protect your yard and plants before the freezing temperatures arrive. Also listed below are things you do after temperatures rise again to ensure that your plants hang around for a while longer.
BEFORE A FREEZE
Remember to mulch the soil around plants and shrubs. Mulching protects the roots of plants and helps to minimize heat loss. Mulch can also help retain soil moisture.
Plant parts that touch plastic during a freeze likely will be damaged. This is why you should cover exposed plants with a blanket first and then with plastic. Make sure coverings drape to the ground. Anchor them with rocks, bricks or soil to keep wind out and allow heat retention. Remember to remove these protective coverings from the plant canopy after cold temperatures have passed
If it is not going to rain before the freezing temperatures arrive, you should water plants thoroughly. This is because moist ground stays warmer than dry ground. Watering the night before the freeze arrives will insulate the root structure of the grass and plants, decreasing the potential for cold injury.
AFTER A FROST OR FREEZE
Check the water needs of plants after a freeze. Water that is still in the soil may be frozen and unavailable to the roots and plants can dry out. To make sure a plant is getting its needed water, apply water to thaw the soil and the ice. It is best to water in the afternoon or evening the day after a freeze so plants have had a chance to slowly raise their temperature.
After a freeze, soft-stemmed, non-woody plants such as impatiens, cannas, elephant ears, agapanthus, amaryllis, begonias, philodendron and gingers may be pruned back to living tissue. This pruning is optional but does help keep your winter garden looking neat. Damaged tissue that is oozy, slimy and foul-smelling should be removed. The decaying tissue is unhealthy for the plant.
Generally, it's a good idea to delay hard pruning of woody plants such as hibiscus until new growth appears in late winter or early spring. Pruning plants now can make them more vulnerable during cold temperatures. Also, in the spring, the damage from cold temperatures will be more obvious so you can more easily remove the damaged parts of the plants.
To determine if the wood of a plant has been injured by the cold weather check the layer directly under the bark by carefully scratching through the bark layer. Undamaged plants will show a green layer, while injured plants will show a brown or black layer. Prune the plant’s wood below the discoloration.
In cases of really sever cold weather and when temperatures fall below 20 degrees, the less hard hardy plants many not make it, regardless of your precautions. Even more hard plants may be injured from extreme temperatures. These freezing temperatures could be an opportunity to remove the plants that don't survive and to start anew when warmer temperatures arrive!