Winter freezes can damage tropical plants in our landscapes. Tropical container plants left outside during freezes are especially vulnerable to the cold. Ideally, they should be moved indoors or into a garage where they will not be exposed to freezing temperatures. If you took a chance and left container tropicals outside and they sustained cold damage, learn from this. Make a point of bringing outside container tropicals indoors in the future if you want to prevent damage.
For tropical plants growing in the ground, don’t be overly distressed if you carefully covered and protected plants and they still show freeze damage despite your efforts. When we cover tropical plants, we do not expect them to come through the freezes in perfect condition. Damage almost always occurs to plants that are covered when temperatures reach the low 20s or lower. For plants growing in the ground, cold protection is done to preserve the life of the tropical plant — not to bring it through the winter without damage.
To maximize protection from covers, make sure the cover extends all the way to the ground and is sealed. Multiple layers of cover provide more protection than a single layer. Providing heat under the cover is best when temperatures will reach the low 20s or teens. This is often done by generously wrapping and draping a plant with small, incandescent outdoor Christmas lights under the cover.
The question I get most often from gardeners after major freezes is usually, “Is my plant still alive and will it recover?” This is a hard-to-answer question for individual plants. There are way too many variables. You will have to evaluate this for yourself. I would say generally be optimistic for plants growing in the ground, particularly if you were able to provide some protection.
The second concern is, “What should I do to help my plants recover?” Unfortunately, the damage is done. Nothing you do now will take that away. If the plants survived, they will recover if you simply leave them alone. If they didn’t make it, nothing you do will bring them back. Do not fertilize, water excessively or do anything like that now.
It’s a good idea to delay pruning after a freeze has damaged plants. Generally, don’t prune anything for a week after a freeze event. It commonly takes several days for all of the damage to be evident.
Pruning Herbaceous Plants
Damaged growth on herbaceous or non-woody plants, such as cannas, elephant ears, birds-of-paradise, begonias, impatiens, philodendron and gingers, may be pruned away back to living tissue. This pruning is optional and is done more to neaten things up than to benefit the plants. However, if the damaged tissue is oozy, mushy, slimy and foul smelling, it should be removed.
Pruning Woody Plants
Dead leaves on woody tropical plants, such as hibiscus, tibouchina, angel trumpet, croton, ixora, schefflera, copper plant and rubber tree, can be picked off to make things look neater. If you can clearly determine what branches are dead on a woody plant, you can 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. 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 are alive and what is dead.
As additional winter freezes occur, continue to 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. They may eventually resprout from the base of the plant or the roots in April or May.
Article by Dan Gill at LSU Ag Center.
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