Right now–the dead of winter, when woody plants are completely dormant–is one of the best times of year to prune. Because I have a small garden and many of my shrubs want to be larger than I want them to be, I do a lot of pruning every winter. And today it was neither raining nor 10 degrees outside, so I pruned three large shrubs.
The way to keep the size of a large shrub under control is to remove individual canes close to ground level. Each year, you remove a few of the largest branches. This keeps the shrub vigorous and helps maintain a compact size. This rule holds for all multistemmed shrubs, including lilacs, viburnums, dogwoods, aronias, serviceberries, hydrangeas, forsythia. If it’s a woody plant that produces multiple stems, this is how and when you prune it.
Most people try to prune shrubs totally incorrectly: they cut off the tops of the branches, as if they were giving the poor shrub a bad haircut. The shrub responds by putting out lots of small branches just below the cuts, and the result is something that looks like multiple witches’ broomsticks. Not to mention a shrub that is wider and almost as tall as before and that retains all its oldest wood.
So here’s how you should do it: Select up to one-third of the canes, the largest ones, and cut them off as close to ground level as you can, making clean, angled cuts so water will not pool in the cut surface. You may have to remove a few smaller canes to allow you to reach the large ones, but that’s OK. This technique reduces the overall size of the shrub, encourages it to produce new, vigorous branches, and increases its overall health and vigor.
Today I pruned a large American hazelnut (Corylus americana) whose branches were getting too close to our front walkway; a black chokeberry (Aronia melanocarpa) that was blocking part of the sidewalk; and a cranberry bush viburnum (Viburnum trilobum) that’s planted too close to the back door. The pictures show how I pruned the hazelnut in detail:
The base of the hazelnut is at the center of the picture near the bottom. Note how may stems there are and how the plant is leaning over the walkway. This shrub has been in place for over 10 years and has reached a mature height of more than 12 feet. We pruned it pretty severely last winter, and it responded by blooming and fruiting heavily last year and producing a lot of young stems. Today I decided to remove just the two largest canes.
Here’s what the shrub looked like after pruning–notice the two cuts, made diagonally through the stems:
And here’s a detail of the two cut stems, which were made with a handsaw:
Unfortunately we’re due for a storm tomorrow, because I really want to get out there and prune. It makes me feel as if spring will really come.