This morning I awoke to find the thermometer reading 10 degrees. I had to rub my sleepy eyes and look again at the read-out of my remote thermometer. The forecast was for 14 degrees, and I admit I didn’t think about it much last night after I returned home late from the movie theater. It has been unusually cold for this part of Georgia for far too many days and I guess I have become a little jaded to the cold temps.
I’m a little concerned about this.
Ten degrees is the upper end of the threshold where we typically find serious winter damage to trees and shrubs. There are several factors that contribute to this, including the species of the plant, it’s location, or micro climate, in the landscape, available moisture in the soil, and how well the plant is acclimated to cold weather. Rather than fret over all the details, the only practical approach is simply to wait and see what the damage may be.
Winter damage usually will not be apparent until the weather warms. Today’s forecast says we may have at least 48 more hours of temps below 32 degrees, which is extraordinarily unusual for this area. After the thaw, the injury may take 2 days or 2 weeks to become apparent. I look for brown or black limbs, especially on the north or northwest side of the plant. Look for leaves with brown or black edges, or sometimes they simply look wilted and dull green rather than a shiny green.
After I’m sure I have waited long enough for the damage to show, I cut off the dead parts. It’s important to cut off the dead parts because the ‘dead’ can spread if it’s ignored. The other issue I have to consider is the looks of the plant. If I go hacking off dead limbs I can ruin the looks of a plant. If the damage is severe enough I may have to cut off a good many healthy limbs to maintain the shape of the plant.
In addition to shrubs, young, thin-barked trees may show long splits or cracks in the lower trunk. In extreme cases frost cracks can be so extensive that it kills or stunts the growth of the tree. I have noticed this particularly with Crepemyrtles, Red Maples and young Oaks that have been planted in a landscape. I have not noticed splitting on young native trees and I don’t know why. I wonder if anyone has done a study on that?
Treatment of frost-damaged trees is a little different but no less important. As the damage becomes evident, the bark will usually shield or cover a dead area that will eventually rot out and leave the heart wood exposed. The extent of the damage can take several months to a year to show, so I have to be patient before I treat. Trees don’t heal from an injury like we do so the treatment is different. By late this summer or early fall I will inspect trees that have frost cracks from this winter. I’ll determine the extent of the wound and how much dead or loose bark is covering it. I’ll cut that bark away with a fresh blade in my box knife, exposing the entire injury area to the air. Without this, bugs, disease, and rot-inducing moisture can be harbored underneath. Cutting away the bark allows it to dry and continue the healng process. In the next year I will look for the edges of the injury to look ‘rolled’ or like it has a lip on it. This is called callus tissue and is a sign that the healing is continuing in the right direction.
Frost crack on a tree
Several things can be done to prevent or minimize frost damage to plants in the landscape, but that’s for another post.
Post Script: It’s been a full month since that Saturday morning when the thermometer dipped to 10 degrees. I have seen some mild or limited damage to Camellia sasanqua in the form of leaf burn, but nothing significant.
Later that day (after I posted) I noticed another type of frost damage. My irrigation well plumbing had ruptured and was gushing all over the ground. I confess with all the rain we’ve had I had not used the well in a while and had neglected to winterize it. (DOH!) I now have a reminder in my Blackberry to drain the pipes next November.
Hello there and thanks for posting this. I live in Minnesota where I planted a bare-root mulberry tree in September. I received it 6 feet tall and it had no leaves on but was very much alive. After the bitter but relatively mild winter we’ve had this year, it’s yet to show any activity in its buds but scratch testing is positve everywhere on the tree and there are no stiff limbs.
Last week I noticed that in many areas above the main branching point, the bark was peeling off. It was paper thin and underneath it there was a white speckled texture that was rough to touch. I peeled all the loose bark off and rubbed that white substance off with my bare hands, exposing slightly green wood underneath.
It was also starting to form new shoots close to the ground. I quickly removed those because I wanted to encourage growth from higher up in the tree. I wonder what I should do about this whole situation. Should I simply wait for the buds to open? Should I chop the tree and make it grow from its main stalk? Should I spray it with fungicide?
Thanks in advance.
Hani,
A mulberry is gonna have a tough time in Minnesota. They are only marginally hardy here in North Georgia. The only living part of that tree is low down on the trunk. It is trying to sprout and grow and you are rubbing it off! The upper parts are most assuredly dead, so the only growth is going to be low on the trunk. My suggestion is to allow it to grow and become a multi-trunked tree…and hope it gets more established before the next harsh Minnesota winter! Let me know how it does through the summer.
Thanks! I’ll keep you posted.