Care for plants that are freeze-damaged

LSU AgCenter News
January 02, 2008 at 11:39 am  | Mobile Reader | Pring this storyPrint 

Although winter temperatures in Louisiana are generally relatively mild, they are punctuated by periods of moderate to severe freezes. Freezing weather is often followed by extended periods when temperatures stay above freezing.

Prior to a major freeze, most gardeners will make an effort to protect tender tropical plants in their landscape. So what should be done for the landscape after a freezing episode is over? Here’s some general information on what to do and not do.

Plants in pots

Any container plants that were brought inside for protection may be moved back to their location outside unless you intend to keep them inside all winter. If you will keep them inside, make sure they are close to windows and receive plenty of light. You cannot keep plants inside dark garages or storage sheds for extended periods of time. Plants must have light to create the food they need to live, and they will slowly starve if not provided enough light.

Covered plants

Many gardeners use a variety of covers to protect plants from freezing temperatures. Remove or vent clear plastic covers on plants to prevent excessive heat buildup if the next day is sunny and mild. The plastic will let in light and trap the heat, just like your car with the windows rolled up.

You do not need to completely remove the cover if it will freeze again the next night. You may leave plants covered with blankets, tarps, opaque plastic or fabric sheets for several days without harming them, but eventually the cover will need to be removed so they can get light.

Pruning damaged plants

Even though you may see damage immediately, do not prune anything for a few days to a week after a freeze. It often takes several days for all of the damage to be evident.

Damaged growth on herbaceous or nonwoody plants, such as cannas, elephant ears, agapanthus, amaryllis, birds-of-paradise, begonias, impatiens, philodendron and gingers, may be pruned back to living tissue. This pruning is optional but does help keep the winter garden looking neat. Damaged tissue that is oozy, mushy, slimy and foul-smelling should be removed. This decaying tissue is unhealthy for the plant.

Remove the damaged foliage from banana trees, but do not cut back the trunk unless you can tell that it has been killed. It will look brown, feel mushy and loose in the soil and will bleed if punctured. If it’s alive, allowing the trunk to remain increases the chances of fruit production next summer.

Dead leaves on woody tropical plants, such as hibiscus, croton, ixora, cassia, bougainvillea and copper plant, can be picked off to make things look neater. If you can clearly determine what branches are dead on a woody plant, you may prune them back. Try scratching the bark with your thumbnail. If the tissue underneath is green, it’s still alive. If the tissue is tan or brown, the branch is dead. Start at the top and work your way down to see how far back the plant was killed.

This pruning is optional and will not help the plant deal with the damage. Generally, it’s a good idea to delay hard pruning of woody plants until new growth begins in the spring and you can more accurately determine which parts have survived the winter and what is dead.

Another group of plants that are generally severely damaged or killed by freezes are tender perennial bedding plants such as impatiens, wax begonias, pentas, blue daze, scaevola, periwinkle and coleus.

Get It Growing is a weekly feature on home lawn and garden topics prepared by experts in the LSU AgCenter.

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