Mother Nature’s Moment - June 2019
by: Lesley Bruce Smith
This year Boxwoods, Japanese Maples and honeybees all have something in common. They were all very badly affected by the vicious “polar vortex” freezing temperatures we experienced over the winter. Gilbert and I and our crews have seen more winter kill this spring than we have ever seen before, and for Gil that means in the last 50 years of trimming and caring for trees. It is a sad thing for us and for many of our clients who have lost favorite Redbuds or Japanese Maples or long time hedges of Boxwood. If it is any consolation just know that about 30-40% of the Japanese Maples in our practice were lost through this last winter.
This spring, when I opened up my bee hives, all I found were thousands of little dead bee bodies who had obviously frozen to death in the late winter, even though they had survived many harsh winters before. Winter kill, to some extent, is an inevitability in our harsh Chicago climate, but this last winter was an especially difficult one. We think it may have been caused by a mild spell followed by freezing ice and wintery snow with exceptionally cold temps. Often our plants can withstand steady cold but the non native plants or those that are only marginally hardy in our area cannot figure out how to deal with wildly fluctuating temperatures. They begin to break dormancy when the temperatures rise only to be hammered by subsequent bouts of freezing cold. Our native plants use day length AND temperature to know when to break dormancy, so they are not fooled so easily. Even they, however, can be bitten by late spring ice storms and the delicate new leaf tissue can be damaged while still in the buds that are starting to break dormancy. Something else we have observed consistently over the years, is that Boxwood that are naturally rejuvenated, annually, as opposed to formally sheared, seldom show any signs of winter kill. This is because when we trim, we promote growth, and if an evergreen plant is sheared late in the season the new growth doesn’t have time to harden off before the freezing cold temps arrive.
What to do? Most of the plants we have seen have a combination of partially damaged and totally dead. In examining many of these trees and shrubs, we have given the advise of “wait and see”. If a plant was only partially killed then they will begin to send out a new flush of growth. You should begin to see little leaves emerging by this point in the season. We can tell that something is still alive, even without leaves, by scratching the tender bark of twigs and looking for green underneath. If it is brown and very brittle we know it is gone. It is always ok to take off the dead parts of a plant when you find them. Cut back to something that is living, which sometimes is all the way to the ground. We are often asked about fertilizing, because it seems like it is something “helpful” for the plants, when in reality it triggers a plant to use up all its reserves, leaving it vulnerable to insect and disease attacks. Of course, contacting Arborsmith to review your plants for trimming needs is always the most trusted option for best results. In the worst case scenario, that the plant is completely gone, we should view it as an opportunity to put something new in the garden.