Let’s Face It, Most Of Us Are Not Frost Cloth People

By Kathleen Ferris

When it comes to protecting plants from cold weather, there are two types of desert homeowners: conscientious and casual.

The conscientious have a plan. They are prepared with large appropriately textured frost cloths. These homeowners use a frame to suspend their frost cloths (also called frost blankets) just above the foliage on a sensitive plant or tree. The cloth reaches the ground where the warmth of the soil can rise throughout the night and keep the fragile flora from frostbite.

Ficus trees are very sensitive to the cold. Photo: Dr. Chris A. Martin, Arizona State University

Ficus trees are very sensitive to the cold.
Photo: Dr. Chris A. Martin, Arizona State University

The casual, otherwise known as the rest of us, find that stack of old sheets and blankets in the garage or shed. We do our best to cover the plants, using chip bag clips or safety pins. It’s unlikely we’ll change.

A frost or freeze can be expected in the Greater Phoenix Metro area anytime after Thanksgiving and before Valentine’s Day. If nighttime temperatures are predicted to be 32 degrees or below, cover your sensitive plants before sundown. If the temperature falls below 20 degrees, you can expect even covered plants to sustain damage.

Here is advice from plant and tree experts about protecting your plants in cold weather.

  • If you don’t have frost cloth, cover plants with lightweight cotton sheets or painters cloth that let in air and light. Burlap and blankets, even paper and cardboard will work, but take care not to weigh down the branches. It’s best if the cover reaches the ground and can trap the warm air rising from the soil.
  • No, that old plastic shower curtain or tablecloth will not work. Plastic will freeze and transfer the cold, either burning or killing the plant.
  • If you get up early to go to work, don’t bother to remove the covers. It’s still too cold and you’ll defeat the purpose of covering the plants in the first place. (If freezing temperatures are predicted for several consecutive nights, it’s safe to leave your plants covered for up to a week. Some of your neighbors, however, may not be happy about this.)
  • Small old fashion electric Christmas lights hung or placed near the base of the plant (heat rises) will add warmth to a plant. New LED lights do not create the same heat.
  • Popular tropical plants are most sensitive to cold weather, such as ficus trees, bougainvillea, yellow bells, lantana, fairy dusters, and some succulents. Lemon and lime trees are more sensitive than other citrus trees.
  • Shrubs sheared into balls, squares and triangles are more likely to suffer from cold weather than those allowed to grow with their natural shapes.
  • If you plant annuals, snapdragons, pansies and flowering kale will tolerate the cold better than others.
  • When a cold night is forecast, water tropical plants and trees at their base a day or two before the freeze. (Remember to turn off your automatic sprinklers. Wet leaves and stalks will freeze and kill any plant.) Do not water cactus or succulents. Cactus and succulents withstand the cold far better if their soil is dry.
  • Potted plants are more susceptible to cold weather damage. Place these plants under large evergreen trees, on your porch, or in your garage or shed. Even moving them closer to the wall of your home helps.
  • Place Styrofoam cups on the ends of columnar cactus arms to protect growing tips.
  • Wrap trunks of young or frost sensitive trees to provide them another layer of protection.

Many plants and trees damaged by cold weather will grow back. Yes, they look brown and ugly for winter guests, but the ugly parts help to insulate the rest of the plant from further damage. Wait and trim them in the spring when nights begin to warm up.

Here is the best tip: If you need to cover a plant, save yourself some time and money by replacing it with a hardy native that can shake off the desert’s coldest nights. Frost and freeze damage is nature’s way of telling us what plants don’t belong in our yards.

Find more information about designing, planting and maintaining a desert garden at AMWUA.

For 45 years, Arizona Municipal Water Users Association has worked to protect our member cities’ ability to provide assured, safe and sustainable water supplies to their communities. For more water information visit www.amwua.org.

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