The one good thing I can say about this slow start to this 2015 growing season is that it has been just that: slow. A gradual warm up will delay things a bit, but plants will usually catch up, and by mid-June it will be hard to tell it was so cold in early April.
It is much harder on plants to have a roller coaster of spring temperatures, from early thaws to cold snaps to warm spells and then back down below freezing. Those early warm spells can induce plants to come out of dormancy ahead of schedule, and the tender, new tissue is especially vulnerable to below freezing temperatures. It doesn’t kill a plant to have tip dieback or to lose flower buds, but it can affect that season’s bloom and fruit set.
Check for Winter Damage
You may be wondering how much winter damage your trees and shrubs may have suffered but in most cases, it’s too soon to tell. Grape and apple growers know how to bisect first-year buds to assess internal winter injury but for home gardeners, it is a lot easier to wait a bit longer and see what develops. Check your plants each week and look for signs of buds beginning to swell. You can use your fingernail to scratch off a bit of bark from the end of a branch. If the tissue underneath is green, it’s fine.
You can begin pruning any time now to remove crossed branches, cut out old stems to open up the center of a bushy shrub, or remove lower branches as young trees reach upward. As spring continues, any branches that suffered winter injury will become more noticeable.
Sometimes a branch will die back a few to several inches. Just cut off the dead tips, making the cut just above a healthy bud. Depending on the type, roses often have some degree of dieback. Roses are invigorated by spring pruning, so don’t worry about hurting the plant.
As with any pruning cut, plants can handle nice smooth cuts. If your clippers are leaving torn or ragged edges, sharpen and tune them up or come back with a better pruner to smooth out the rough edges of the wound. There is no need to use any kind of pruning paint on any cuts, no matter how large the cut. The plant will take care of itself and the paint, especially any tar-based products, can interfere with the wound response.
Assess Chewing Damage
Another kind of winter injury you may notice now is chewing damage to the base of stems and young tree trunks. Voles, field mice and rabbits are the worst offenders here. They use the cover of deep snow as they gnaw away throughout the winter so you are often not aware of any problem until the snow melts.
Unfortunately, there is really nothing you can do repair chewing damage. If the bark is chewed off all the way around the stem, that stem will eventually die from that point up. If the damage is only part way around, the remaining tissue may be able to sustain the plant, but you just have to wait and see.
The tissue just under the bark is called the cambium layer, where the xylem and phloem cells are. These cells serve as tubes to carry water and food up and down the stem, from the roots to the leaves and back down again. The chewing damage destroys this vital cambium layer. Young trees may not recover but shrubs can usually send up new shoots from their roots to replace damaged stems.
Photo of Spring crocuses in snow courtesy of Meneerke Bloem.