I have had a few people respond to my article about winter damage showing up already. James R. sent the following note:
“I recently noticed that many of my China Holly’s leaves were ‘burnt’ during the recent cold snap which occurred during this past Christmas season. They have a brown tint and not the normal green color. Will I lose those plants or will they be able to come back from the freeze damage? I’m sure the brutal wind along with the extremely cold temperatures was more than they could handle.”
He was spot-on when he mentioned the brutal wind and cold temperatures. As the air blew across the leaf surface water was lost through evapotranspiration and since the soil was frozen, it couldn’t be replaced quickly. This is called winter desiccation injury.
The result is a browning of the leaves. Depending on the severity, the leaves may green up in the spring or may drop completely. If the stems are green, there is a good chance the plant will survive.
The best thing to do right now is to wait. Watch (hopefully) for new growth in the spring. If this doesn’t occur, cut out any dead.
I noticed something interesting while driving around Clark County back in November and wonder if anyone else has seen this. There are several boxwood hedges that have winter burn symptoms at the tops of the plants.
What made it unusual for me was to see it in November, before it got cold. My suspicion is that it might have been pruned and we got a drop in temperatures shortly after it was pruned. If you remember seeing this prior to the cold spell around Christmas, drop me a note. I would like to see if anyone else had this kind of damage on boxwoods.
Anytime you prune you are damaging plant tissue. If the plant is pruned and then there is a sudden extreme drop in temps, damage occurs. Therefore, winter pruning is a bit risky.
Typically, growers who are going to do winter pruning because of timing issues check the extended weather forecast. You don’t want fresh exposed tissue if there is a predicted cold snap.
I remember several years ago seeing this type of damage in the Secrest Arboretum. The staff needed to prune an overgrown boxwood hedge and the only time they could do it was in November. And the pruning was rather harsh, with the removal of more than one-third of the plant.
December came, along with a drastic drop in temperatures. The next spring, the plants had severe dieback, almost to where the plant had been pruned by two-thirds. The speculation was that it was pruned at the wrong time.
The hedge eventually grew back but evergreens take a long time to regrow, particularly when they are cut back this far.
If you are going to prune this winter, keep this in mind. Otherwise, wait until late February or March to prune. There is less risk during that time.
Pamela Corle-Bennett is the state master gardener volunteer coordinator and horticulture educator for Ohio State University Extension. Contact her by email at firstname.lastname@example.org.
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