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Dealing with cold damage

By CARTHY DUNN - | Jan 19, 2023

Use landscape cloth to cover plants to protect them from the cold. University of Florida/IFAS

The last several months have been very discouraging for me as a gardener. Ian ravaged my landscape, and I spent two and a half months removing debris, propping up fallen trees and shrubs, carefully pruning and shaping my plants, applying a layer of mulch and sustaining them with food and water. I was rewarded for my efforts with fresh foliage, new blooms and a garden plan that was rejuvenated by the removal of excess plants that no longer fit my landscape design.

Then the long, windy, cloudy, cold spell struck at Christmas, and I felt that my efforts had taken a huge step backwards. All that tender new growth was burned by the lower temperatures and wind, and all of this happened in just the first few days of winter! Regrettably, we’ve had another stretch of very cool nights just this past week. We can certainly expect another cold snap over the next 2 months, and the thought of further setbacks has me anxiously monitoring the long-range weather forecasts.

Even though we don’t usually confront the freezing temperatures that north and central Florida can experience, many tropical plants suffer “chilling injury” at temperatures below 50°F.

How can you recognize cold-damaged plants? Cold can affect either an entire plant, such as annuals like begonias or impatiens that appear to collapse, or just the more susceptible parts of a plant such as fruits, flowers and roots. Plants can also desiccate, or dry out; you might notice brown leaf margins or leaf tip burn, or in severe cases, totally yellow or brown leaves. This desiccation is usually caused by dry winds associated with cold fronts that move into our area from the north, causing water loss from leaves that cannot be replaced by a cold root system. This damage is not always immediately apparent; after the December cold spell I thought my plants had escaped damage until about a week later when leaves suddenly yellowed and dropped.

Fortunately, there are some practical steps that you can take to protect your plants. Potted plants should be moved either indoors or onto your enclosed lanai or porch. I bring tender plants into my lanai and close the storm shutters; this keeps the temperature above 50 degrees, and also protects the plants from the drying winds. Plants that can’t be moved should be covered with landscape cloth, which can be found locally or ordered online. The covers must extend to the ground to trap radiant heat and should be anchored with bricks or rocks. I used sheets to cover plants in December, and while they were helpful, the landscape cloth is significantly lighter and does a much better job. DO NOT use plastic to cover your plants, as the plastic will actually transmit cold air to your plants!

A thorough watering before a cold spell is beneficial to plants because it actually helps retain heat in the soil and provides a ready source of moisture to help desiccated plants once the temperature rises. Based on what you have heard about farmers protecting their crops with irrigation prior to a cold spell, you may be tempted to run your irrigation system; this is not recommended since residential irrigation systems are not configured to supply water in quantities sufficient to maintain a film of water on the leaves as commercial systems do.

What should you do if your landscape has suffered cold damage? First, don’t despair; with patience and care, most of your plants will recover. Check the soil around your plants for moisture; once the sun is out and the temperatures are climbing, water can help warm the soil and provide the necessary moisture that even injured plants require.

You may be tempted to fertilize your plants to assist them in their recovery, however, if you apply fertilizer too early and we have another cold spell, the tender new leaves will be the first to be damaged. It is better to wait until March when the danger of cold weather has probably passed before you add fertilizer to your garden.

Cold-damaged plants should not be pruned immediately; while the dead foliage is not attractive, it will help protect the rest of the plant from further damage. In March, you can check the viability of the plant by scraping the bark with your fingernail; a green layer under the bark indicates that the plant is healthy and you should prune to that point on the branch.

Any annuals that have collapsed should be removed from the garden immediately as they will not revive and could promote viral or bacterial growth in their decaying material.

I believe that gardening is always a leap of faith buoyed by confidence that our knowledge and experience will result in a beautiful green oasis. But Mother Nature sometimes has other plans, and we need to be prepared to respond to her whims!

It is sometimes difficult not to become discouraged when our gardens are affected by cold weather, but with good preparation and care after the cold weather, our gardens will soon be thriving in our subtropical climate.

Cathy Dunn is a Lee County Master Gardener Volunteer and a member of the Garden Club of Cape Coral. Visit us at www.gardenclubofcapecoral.com.