Be patient when it comes to dealing with freeze-damaged plants

The snow has come and gone — and so has the excitement that came with such a meteorological rarity in Louisiana. Now, some gardeners are looking outside at a far less enjoyable sight: plants that turned gray, brown and perhaps even mushy in this week’s frigid temperatures.

Tropical and subtropical plants were especially affected by the bitterly cold air that hit the state. Damage may even be visible on azaleas and other woody ornamental plants that are normally hardy.

Don’t panic. While they may not look their prettiest, most plants will do better in the long run if they’re left alone for now, according to LSU AgCenter horticulturist Jason Stagg.

“Seeing all that dead top growth makes us want to immediately rush out, cut everything back and clean up the garden,” Stagg said. “But that’s not usually the best course of action for the plants themselves.”

The complete scope of freeze damage isn’t always immediately apparent, and plants that appear to be dead may in fact still be alive. That’s why Stagg recommends waiting until spring to prune affected plants.

“Once the plants start regrowing and new buds start emerging, only then can you tell how far the plant truly died back,” he said. “Pruning before then could prematurely cut off too much viable tissue that the plant can regrow from.”

There are other good reasons to put off pruning. The remaining stems, even if they’re unsightly, will help protect plants from further damage as winter wears on. They also provide overwintering habitat for beneficial insects.

For those who just can’t wait, Stagg has a few pieces of advice:

— Prune only enough to clean up plants, leaving as much of the stems as possible. Don’t cut plants back all the way to the ground, which will leave them even more vulnerable in future freezes.

— Avoid cutting off more than one-third of the height of a plant.

— Use a knife or pruners to scrape the stem of plants. If you see green, the plant is still alive.

— The leaves of many tropical plants, including ornamental bananas and gingers, are especially sensitive to cold and will droop when frozen. But the plants themselves are root hardy and will grow back in the spring. Remove all frozen leaves and up to one-third of the stalks.

In the case of cool-season annual bedding plants, determining whether they’ve survived will take time, too. Damaged plant parts — usually the extremities — may look wilted or almost melted and have a dark green color right now. But, given time, these plants often can bounce back.

Stagg suggests waiting at least one week before deciding whether to toss cool-season annuals.

“At that point, it’s easy to tell what plant parts survived and what didn’t,” he said. “For example, petunias and dianthus will usually show healthy, green, turgid leaves at their bases. Violas and pansies may be completely mush within a week — or maybe not. Cabbage and kale as well as dusty miller should mostly be fine but, again, waiting a week will make it easy to tell.”

Feel free to pull up and discard any warm-season plants like zinnias and marigolds that may still be lingering in the garden, Stagg said. They won’t recover from this cold snap.