Long before their leaves begin to drop, trees and shrubs begin preparing for winter. Just as squirrels store food for the long winter ahead, trees and shrubs shift their nutrient supply from their leaves and branches to their roots. Cellular liquid in the trees and shrubs thickens and lowers its freezing point. As this liquid freezes, it forms elongated crystals, shaped to be less prone to bursting the cell walls.
In further preparation, deciduous trees and shrubs drop their leaves. Evergreens increase the waxy coating of their needles and seal off the bottom opening, which allowed transpiration in the summer. All this advance preparation helps most mature trees and shrubs make it through the winter with little or no damage.
You can help protect against the ravages of winter’s weather. Adequate water is perhaps the best insurance you can give your over-wintered stock. Roots continue to take up water even after the leaves have fallen, so continue to water as needed. Be sure to give trees and shrubs a good drink just before the ground freezes, but be careful to not flood the ground. Mulch the root zone with organic mulch to conserve moisture and lessen temperature extremes. When spreading mulch, be sure to keep a gap between the trunk and the mulch. A thick layer of mulch, snuggled up to the trunk, forms a cozy nook for rodents who will also snack on tree bark in the winter, causing life-threatening wounds.
Recently planted trees and shrubs can use additional help to ensure winter survival. Young trees, particularly fruit trees, face considerable winter challenges. Deer graze at their branches, rodents gnaw at their bark. Tree wrap has long been advocated as the simplest method to prevent critters chewing on the bark. Tree wrap, whether the standard rolls of specially-treated brown kraft paper or the plastic snap-on tubes, can be quite effective against small rodents. When applying the wrap, be sure to account for the snow depth. Rabbits on the surface of a 2-foot snow bed, can reach quite high. With warmer spring weather, wraps can create more problems then they prevent, so be sure to remove these barriers as the weather warms.
Fencing offers better protection against gnawing critters. A loose collar of chicken wire, 3-4 feet high, keeps rodents at bay. If deer are a problem, encircle the entire tree with a taller wire fence, being sure to stake it well against the strong winter winds.
Extreme cold and strong winds exact their toll on your plantings. Temperature fluctuations throughout the season can wreak havoc as sap warms in the sunshine, then freezes at night. Tree wrap can help protect the tender bark from temperature fluctuations and the resultant frost cracks.
Protect the more delicate needles of young evergreens from the drying effects of sun and wind with screens. Conventional wisdom suggests wrapping newly planted evergreens in burlap, but wet burlap is heavy and can be harmful. Instead, stretch burlap between wooden stakes, creating a screen to shield against the drying effects of harsh sun and strong winds. After the first 1 or 2 years, evergreens should be hardy enough to survive winter unsheltered.
When snow lies heavy on the tree branches or the top of shrubs, branches can break. Gently shake branches or brush shrubs with a rake or broom. Careless snow removal can cause more harm than good so remember to be extra careful. Before the snow flies, prune weak or damaged branches.
As long as your plantings are considered winter-hardy, they should survive our winters quite nicely, but it never hurts to offer a helping hand.
Beverly Carney can be reached at cultivating firstname.lastname@example.org.