It depends on what they are, where you live, and what you do.

By Steve Bender
February 16, 2021
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As I write this, it's 20 F. degrees in Corpus Christi, Texas, 13 degrees in Houston, 1 degree in Dallas and Memphis, and minus 10 degrees in Tulsa. Here in Birmingham, it's a balmy 15 degrees with massive snowdrifts upwards of one half-inch. I don't understand. Don't Southerners live in these places to escape winter cold? There can be only one explanation.

Sorcery!

Nah. The true cause is a bizarre loop in the jet stream blasting Arctic air all the way down to the Gulf. It won't last that long, but in the meantime surfers in Corpus Christi are advised to dress warmly.

What are the consequences for plants? Well, if you're one of those conservative gardeners who plants only things native to your area that are used to the climate, they'll probably be fine. On the other hand, if you live in Tulsa and amaze your neighbors with tropical displays of Chinese hibiscus, Norfolk Island pine, banana trees, orchid trees, and mandevilla, dust off your chainsaw, pruning saw, and loppers. You're gonna need 'em.

Credit: Steve Bender

After the Blast Checklist

Though the current deep freeze won't last that long, the damage to plants probably will. Here are some serious and not-so-serious signs to look for.

Dead, brown flowers.

Hope you enjoyed the last couple of weeks filled with blooms from camellias, Japanese magnolias, quince, early daffodils, flowering almond, and other things. Temps below 25 degrees turn open blossoms into brown mush. Oh well, there's always next year. On the positive side, damage to the plant itself may be limited to the blooms.

Deep green foliage on broadleaf evergreens that turns black and brown.

What's happened here is that ice crystals burst the cell walls inside the leaves, killing them. The leaves will likely drop, but don't rush to prune the sad-looking victims. The stems that held the leaves may or may not die back. Wait until spring to see if the plant leafs back out or if it is kaput for good. Scratch the bark to see if you can find a green layer underneath. If you can, that part of the branch is still alive. If not, it isn't. Provided the plant is salvageable, you'll want to cut it back to the highest point on each trunk and branch where you can find green.

Split bark.

This is bad. This happens when a huge temperature swing happens in a short time. Water freezes inside the trunks of trees like crepe myrtles and splits them vertically. Split trunks usually die to the ground. Worst case scenario – the whole tree dies.

Credit: Steve Bender

Pre-Blast Checklist

The big freeze is moving west to east, so those of you along the East Coast are next in line. Here are some things you can do to mitigate damage to your plants.

Bring indoors pots containing plants that aren't super-hardy.

Potted plants are much more susceptible to cold than those in the ground because their roots are exposed to the frigid air. Don't worry about finding them a sunny spot, as well they won't be inside that long. An unheated garage that doesn't go below freezing will be fine.

Insulate tender plants you can't bring inside with leaves, mulch, straw bales, etc.

Snow is a great insulator if you have it. I planted a small 'Spider's Web' Japanese fatsia last spring, because my friend and Charlotte garden designer Jay Sifford likes plants that look like they've been devoured by spider mites. It's kind of iffy in my USDA Zone 8A garden, so before the storm, I mounded oak leaves on top of it and then topped the mound with a plastic bucket. Snow now sits atop the bucket, so maybe I saved the dang thing.

Turn off the water to outside faucets and empty garden hoses and unheated birdbaths.

As ice freezes, it expands and bursts things.

Don't use rock salt to melt ice and snow near plants.

Salt is poisonous to plants and destroys the soil's structure so that it no longer drains well. Instead, sprinkle a little lawn fertilizer or sand over icy spots. No, they don't work as well as rock salt, but your plants will thank you.