An unusual year yields interesting questions about plants, trees and cold damage

As a gardener, I’ve never lived through a stranger year.

The winter of 1983-84 was odd, but this one proved worse. The questions keep pouring in. I’ve herded them together and I’m going to do so one more time as we finish the year out. Here are the ones people are still asking and how I’m responding.

“Why are there vertical cracks in the bark of my tree, and will it survive? Is there anything I should be doing to help it?”

Just to grant it Favored Question Status, this one cropped up by the middle of March and it’s only gotten more common as the months have rolled along.

This is a phenomenon known as “radial shake.” Bark and trunk tissues, faced with many consecutive hours of extremely low temperatures, developed vertical stress fractures. They were first noticeable in the bark.

As it began to peel away from the trunks, the inner woods of the trunks were left exposed and vulnerable to the drying conditions. Things went downhill, and trees’ canopies began to lose leaves. By now some trees have become entirely bare since mid-summer. Others have sent up sprouts from their roots. Many others are trying to heal.

Species impacted included ashes (devastation has run high – many trees were lost entirely) and, to lesser degrees, Shumard red oaks, live oaks, Chinese pistachios, lacebark elms and too many others to call out individually.

Now, 10 months into all this, our bigger concern comes back to the remaining vigor of the surviving trees. Can those that were granted glancing blows survive and recover? Would they be able to remain standing were a strong ice or windstorm push through against them? If one of the weakened trees were to fall, would it hurt someone or could it do damage to other plants or property? You may want to hire a certified arborist to help you assess the risks. It may be time to have the tree taken down.

“Is it safe to replant new shrubs at this time? I’ve located them at my favorite nursery.”

Absolutely, yes! Obviously you would want to avoid species that are marginally winter-hardy where you live, but all the others should be just fine. As people rush to do their spring landscaping makeovers in March and April we’re likely to see one more round of shortages of plants, so if you find the ones that you want now, you’ll be way ahead to get them planted.

There seem to be ample supplies of larger plants, and that’s a good thing. Those larger plants gain you several years of head starts, plus you have a greater margin of error in watering. Remember that new plants should be watered by hand for their first couple of years in your landscape. Sprinkler and drip irrigation alone simple will not be adequate.

“What can I do to prevent the same kind of cold damage to my new plants this winter?”

First things first: Remember that what we experienced last February was probably a once-in-100-years cold spell in terms of low temperatures reached and how long it stayed cold. Add in the fact that it happened so late in the winter (just before things started to bud out and bloom or start growing), and you can see why it was such a rare occurrence.

All of which is to say, don’t obsess excessively over the chance that it might happen again. Stock up on enough frost cloth to cover plants that could be damaged (i.e., those hardy to Zone 8 or 9), and keep everything watered well over the winter. The soil doesn’t have to be wet, but you just don’t want plants to go into freezing weather lacking for water.

“In light of the cold damage, when can I prune my plants? I don’t want to make things any worse.”

Usually those dates come with the specific plant named, and that will determine the correct answer. In general terms, however, shade trees are pruned from now until late winter– sooner rather than later if dieback due to cold damage has been involved.

Evergreen shrubs are trimmed while they’re dormant in late December or January. Spring-flowering shrubs and vines are pruned immediately after they finish blooming in spring. Summer-flowering shrubs and vines are pruned in winter, but never “top” crape myrtles.

Grapes and fruit trees, most notably peaches, plums and apples are pruned in late December and January. Read how each should be pruned so you’ll do it correctly. Do not do much pruning to pears, figs or pomegranates except to remove damaged branches. Blackberries are not pruned until after they finish producing, at which point all canes that just bore fruit are cut to the ground.

“Should I leave the fallen leaves on my lawn, or should I remove them? Can I run them through a mulching mower? Will they help protect my lawngrass from winter’s cold?”

Bermuda and zoysia grasses are quite winter-hardy here in North Texas. They should have no problem surviving our cold, even if it’s as extreme as what we faced in February 2021. St. Augustine is less durable, but for whatever the reason, it wasn’t hurt as badly as many of us feared. Undoubtedly, the snowpack that covered it also protected it.

To your answer, leaving fallen tree leaves on top of the ground is not a good plan. They pack down and trap warmth and moisture. That combination leads to disease and it also increases the likelihood of winter kill should the leaves blow away in a severe winter storm.

Use your mulching mower to return them to the lawn’s surface 49 or 50 weeks out of the year, but when the biggest batch of them falls in November, run them through the mower and then use the mulched leaves in the compost pile or as an actual mulch beneath shrubs or around perennials. They’re worth their weight in gold.

You can hear Neil Sperry on KLIF 570AM on Saturday afternoons 1-3 pm and on WBAP 820AM Sunday mornings 8-10 am. Join him at www.neilsperry.com and follow him on Facebook.