Freeze-damaged herbaceous tissue that gets mushy and leaks liquid should be removed. (Photo by Dan Gill, LSU AgCenter)

Generally, avoid pruning freeze-damaged woody plants until spring when you can identify dead tissue. You can scratch the bark of woody tropicals to see if they are alive. (Photo by Dan Gill, LSU AgCenter)

Green tissue under the bark indicates the plant is still alive. (Photo by Dan Gill, LSU AgCenter)

For Release On 01/01/16

By Dan Gill
LSU AgCenter Horticulturist

The relatively mild winters we have here in Louisiana allow us to grow a variety of tender tropical plants in our landscapes. They will often survive typical winters around the state, although south Louisiana gardeners have more successes, particularly if plants are provided some protection.

Even with protection, tropical plants are almost always damaged in some way during winter freezes. Here’s some general information on how to deal with tropical plants after a freeze.

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 freezing temperatures are forecast for 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 it 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, be loose in the soil and 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, tibouchina, angel trumpet, bougainvillea and copper plant, can be picked off to make things look neater. If you can clearly determine which branches on a woody plant are dead, 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 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 used for summer color, such as impatiens, wax begonias, pentas, blue daze, scaevola, periwinkle and coleus. Although it’s nice when they make it through the occasional very mild winter and provide another year of flowers in our landscape, we must remember these plants are not intended to be permanent.

If, or when, summer bedding plants have been killed by subfreezing temperatures, remove the dead plants from the bed and mulch over the area to keep it looking neat. You could also prepare the bed and plant hardy cool-season bedding plants such as pansies, dianthus, alyssum, snapdragons or many others. These may be planted anytime now through early March for an outstanding display this spring.

Remember, there is still plenty of time to see additional – and possibly more severe – freezes before it’s all over. Protect what you can when needed. Don’t be too quick to dig up and remove tropical plants that have been severely damaged and appear to be dead. Sometimes, they may eventually resprout from the base of the plant or the roots in April or May. Despite what comes, remember that our climate encourages rapid growth and recovery.

If worse comes to worse and you do lose some of the tender tropical plants in your gardens, don’t think if it as a tragedy but as an opportunity. When the dead plants are removed, we will have open areas available to plant. Think about that, and the loss might not seem so bad.

Rick Bogren