Winter's Effect on Your Landscape
by Don Janssen, Extension Educator
With winter on the horizon, a variety of forecasts are made as to precipitation and temperature expectations. While it is difficult to predict the actual weather winter may bring, predictions can be made as to the effect of various conditions on landscape plants.
November has been quite mild. For tree and shrub health, a gradual transition into bitter winter cold would be best, rather than a quick extreme temperature drop. Drastic fluctuations and prolonged periods of sub-zero temperatures can injure many trees and shrubs, particularly those marginally hardy for our area. Buds, twigs, and entire branches may be killed. Next season low temperature injury may show up as the lack of flowering, or a plant appearing to resume normal growth and then suddenly wilting and collapsing.
In addition to bitter cold, winds of winter may cause desiccation injury to plants. Above ground plant parts dry out because water cannot be replaced from frozen soil. Evergreens of all types are most susceptible, including needle evergreens (yews) and broadleaf evergreens (rhododendron, boxwood). Most areas have had adequate rainfall this fall, which helps decrease injury potential, but winter conditions will dictate what damage may occur.
While opinions vary on the desire for snow, significant snow cover provides excellent insulation of the soil. This helps protect perennials, bulbs, ground covers, and strawberry plantings from alternating freezing and thawing cycles that can lead to soil heaving. This is the major reason winter mulches are put over perennials and related plantings. Straw and evergreen boughs are good choices for mulching beds in the upcoming weeks.
Finally, winter weather impacts pests. Sub-zero temperatures can help reduce some insects, such as those overwintering as egg masses on trees. Snow cover provides shelter from predators for pests such as voles, which do damage to lawns. Rabbits also tend to cause more damage to trees and shrubs when there is extensive snow cover.
(This resource was last updated November 2005 and appeared in the Lincoln Journal Star Newspaper Sunday edition. For information on reproducing this article or using any photographs or graphics, read the Terms of Use statement)
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