Alberta Story: What to wrap?
What in the garden should you wrap for winter?
Wrapping can do more harm than good as wrapping materials such as burlap can actually wick away moisture from the very plant you are trying to protect. This is especially the case with evergreens such as cedars, which continue to exude water all winter long.
So what should you do to keep that evergreen from becoming brown over winter? First, consider where you are planting that prize tree. If it has a south-facing exposure with lots of sunlight, it is in danger. If it is a north facing area with prevailing north winds, it is in danger. Elevation will also matter: higher on a hill means more exposure to wind and sunlight, the two enemies of moisture.
Instead of wrapping, build shelters. A tripod-supported burlap wrap will do the trick as long as the branches don’t touch the burlap. Even a simple wind or sun break will work.
Young fruit trees which have thin bark should be protected from direct sunlight in March, when days can be warm and nights drop below freezing. Sunlight can also be reflected off snow, magnifying its effect. The cells expand as the trunk or branch of the tree absorbs heat from the strong March sunlight, then contract when the night turns cold. This freeze-thaw cycle causes cells to burst resulting in splitting bark. This may heal itself, but it may also become infected with disease or infested with insects.
Again, shelter in the form of a shade barrier is a better answer than wrapping. Even roughing up the snow in front of the tree in March can help to decrease the heat of the sun, but some sort of screen is a better alternative.
Note that all trees are more vulnerable in their youth, before barks harden and furrow, which helps to deflect sunlight.
Wrapping roses is thought by some to be a good idea, too. One gardener in Calgary used to knit cosies for her roses! But, really, the hardy roses bred in Canada need no protection; you can to add some mulch to the root zone of new roses just to get them through the first winter or two, but most are fine without. Any wood exposed to the air may die back to wherever the snow reaches, but new wood will emerge in spring.
If you are a bit of a rosarian and want to try more tender varieties, there are rose covers made of Styrofoam that you can fill with leaves and place over the plant to protect more of the wood throughout the coldest months.
By Dorothy Dobbie