When the great March snowfall struck the Willamette Valley, I was basking in unseasonably warm New York sunshine. As we landed in Eugene a few days later, piles of grayish snow at the airport were still evident. But by far the more powerful testimony was the carnage we saw among the trees. The streets were mostly cleared but broken branches were piled everywhere, in front yards, medians and park strips. The first thing we noticed was that most of the destruction seemed to involve purple leafed plums, which had been in full, ravishing pink bloom when the snow fell.
Many magnolias were also in bloom, as were white-flowered Japanese plums. Neither sustained the kind of damage inflicted on the unfortunate pink plums. These are weak-wooded trees with a miserable growth habit, at least when grown in a wet climate, and I personally think far too many of them are planted. I guess the combination of rapid growth, showy pink bloom and purple foliage is irresistible. And I have to admit that heavy, wet snow is a relatively rare event in Eugene. In one respect, the trees were lucky. A few degrees warmer, and we might have had a severe ice storm, with much greater and less selective consequences.
Trees that were not in bloom suffered as well, especially those with densely twiggy, snow-catching structure. Dogwoods and Japanese maples lost only minor branches, but some trees in my neighborhood that I tentatively identified as Chinese or lacebark elm (Ulmus parvifolia) suffered the same kind of profound failure as so many of the plums, with major limbs snapping off entirely or tearing away from the main trunk, leaving heartwood exposed.
Whatever the type of tree, that kind of damage involving the main trunk is essentially fatal. The kindest thing to do is to have the tree removed and plant another. Trunk tears may heal, after a fashion, and a plum will readily send up suckers from truncated limbs, but the tree that results will be compromised forever, risking heart rot and weakly attached branches. If the tree is young, you can try cutting it flush with the ground. Plum trees are usually more than happy to respond with new growth. Later you can select one or more of them to form new trunks.
Where storm damage isn’t quite so bad, surgery may be worthwhile. Severely damaged branches should be cut off as soon as possible, at the point where they join a larger limb or the main trunk. Oaks and Douglas firs have a habit of dropping large limbs, rather than tearing away from the trunk. Remove the stubs with a clean cut. Also prune away broken wood on smaller limbs over an inch in diameter. Clean cuts heal better than tears, with less likelihood of fungal infections that may shorten the life of the tree. Shrubs will also be better off if broken branches are removed.
Another common form of damage that results from heavy snow, especially in conifers such as arbor vitae and Italian cypress, is the splaying outward of branches. Sometimes they split off, sometimes not. Splayed but unbroken shrubs can often be saved by carefully re-shaping and tying. Heavy plastic plant tape and old tights are good materials to use. New growth will slowly fill in any irregularities, but the ties may have to remain in place indefinitely, so do the best job you can to make them invisible. Drooping pine limbs will partly recover on their own, but props can help.
When you’ve done all that, April is a good time for some other kinds of pruning. Remove winter-damaged tips from evergreens, if you haven’t already done it. Spring flowering shrubs are usually pruned after they bloom, but now is the time to prune shrubs that bloom in summer on new growth: hydrangeas, roses and Japanese spiraea, for example. I wait until the weather actually warms up before pruning more tender specimens. It’s usually mid to late April before I see obvious new growth and know that it’s time to prune lavender, blue mist shrub (bluebeard, or Caryopteris) and other subshrubs.
What’s a subshrub? Anything you might think of as a woody perennial, like santolina, thyme and culinary sage. Many subshrubs get floppy and out of shape and bloom less consistently if not pruned back on a regular basis. Heather is a great example, but heather is extremely hardy and I usually trim it right after the flowers fade in March.
Another thing subshrubs have in common: their useful life is often a short few years. Trimming regularly helps extend the life of lavender and heather, but they still may need to be replaced after five years or so.