Winter Pruning
The benefits of a good pruning are just too great to merit restraint.
As the light lengthens toward the end of January, I find myself increasingly drawn to our dining room window. From there, I’ll spend ten minutes at a stretch listening to the siren song of my own springtime plans. Maybe I could move a few of those catmints to the front of the border, and make room for more salvias? Or would it be worth investing in some topiary to form an evergreen background for the roses? One of the joys of gardening is the making of such plans, watching the whole season of growth and bloom play out in your mind’s eye as you strive for the ideal. And it doesn’t matter that no garden could ever be perfect, because perfection in this case would mean stasis, and a garden that isn’t moving is dead. Fussing with a garden—just dallying your way through it with a glass of wine on a summer evening, pulling a weed here, deadheading a bloom there—is one of the great joys of the hobby, and the closest we can come to that joy this time of year is to start planning for the growing season.
But there are more practical affairs to take care of in winter as well, namely winter pruning. Not all plants want or need to be pruned before the growing season. Some—most herbaceous perennials for example—simply need to be cut down to the ground around the beginning of March. If, like me, you’ve started to leave your catmints, coneflowers, ornamental grasses, and Russian sages standing over the winter to provide cover for animals and visual interest from your snow-bound window, they are likely starting to look bedraggled and will eventually need to be cut right back to the earth, allowing air and light to fuel the coming season’s growth. But you should restrain yourself as long as possible to give the overwintering moths, rabbits, mice, and birds the warmth and cover they need during the depths of the season.
That said, woody perennials, shrubs, and trees will all benefit from judicious pruning in late winter. Such pruning needs to be timed right and conducted correctly if it’s to be effective, and it can certainly feel intimidating to stride out into your garden and hack off pieces of beloved plants whose blooms you treasured last year. But, given a few guidelines, you’ll be able to make informed decisions about when, what, and how to prune with relative ease.
The first thing you need to know is that, generally speaking, the time of year in which you prune plants results in dramatically different responses. While summer pruning typically restricts growth, winter pruning actually encourages it. Almost all trees, shrubs, and woody perennials will respond to cold-season pruning with vigorous growth come spring, usually in the form of long, blooming shoots that vault upward searching for the sun. By contrast, cutting branches from an apple tree or stems from a rose in summertime will tend to stop them from growing in that direction. The plant has bigger fish to fry at that time of year—namely fruit production—and replacing a clipped branch doesn’t fit into its plans.
You should therefore prune something in winter for only two reasons: either because you want it to grow full and vigorously next year from the location of the cut, or because you’re getting rid of a dead or diseased branch. It’s worth noting—and I was actually getting this wrong for years before I started my research for this article—that you should thus avoid pruning orchard trees hard during the winter, since doing so will cause them to respond with a flush of long, thin, unproductive “water sprouts” in summer which, of course, you’ll only want to prune again next winter, resulting in a cycle of harsh pruning and useless growth that will net you less fruit. In the orchard, then, only bad branches should be cut in winter.
However, there are many plants from whom you want exactly this sort of dense upward growth. Roses are a prime example: any crossing canes should be clipped back to the ground in March, along with a good many from their interior to ensure that air can flow freely through the middle of the plant—a prime strategy for avoiding the dreaded mold issues to which they’re so susceptible. Finally, all of the remaining canes should be cut back by about a third. This treatment may seem very harsh but, if done intentionally and with a good, sharp, clean pair of garden snips, it will result in a dense, vigorous plant whose health is simply better, from roots to bloom.
But where, exactly, should the branches of a plant be cut? Is any place as good as another? Not exactly. The second key piece of general knowledge to take with you is that, when cutting a branch back, you always want to cut back to something. In practice, this almost always means cutting just above an outward-facing bud or node, preferably at a forty-five-degree angle so that any moisture that falls or collects on the cut slides off and away from the locus of new growth. Don’t turn this into a fetish, though: in the thick of battle with a giant, fifteen-year-old rambler that dominates a whole side of your house, it could drive you crazy to try to make every cut with surgical precision. But, as a rule, do try to cut just above a node so that the plant won’t waste energy and nutrition by sending its supplies to a branch that can bear no new fruit.
A few weeks ago, I took my advisees—a small group of boys between the ninth and the twelfth grade—out into the garden on a bitingly cold morning. As I’d come to learn over our many meetings this year, each of them was carrying a good deal of work, worry, and weariness into school each day, and sometimes it’s curative to go out and get some fresh air. Armed with a few pairs of snips, I showed them how to prune one of the Vegetable Gardens’s climbing Iceberg roses. As I began, they protested: the plant was still producing new growth, still bearing leaves! And some roses can indeed do so even in the harsest weather. But the benefits of a good pruning are just too great to merit restraint: whether the plant is frail or healthy, getting knocked back by a loving hand is often the best thing for it. Biblical metaphors abound, of course, for this process. And it would seem that some of that wisdom crept into their minds while we worked: as I handed a clipping to one of the boys, he looked past it, at the now-smaller rose that would soon respond to the setback with a burst of new life, and said quietly, “Like us.”
