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How to Prevent Winter Plant Damage

How your plants will fare during our bouts of winter snow and freezing temperatures depends on many factors. These include how well your plants are sheltered, the hardiness of your varieties, and the maturity of your plants. If your plants are already under stress or if they were in containers, they might sustain considerable damage. Sometimes the effects cannot be seen for months or even years. Here are some guidelines to help you minimize winter plant damage.

One of the best preventive measures to protect plants from winter damage is to do a fall application of mulch to your beds. Adding a few inches of a good organic material to the soil surface will help to insulate the roots of your plants and conserve water and keep your plants hydrated. Leaves that have fallen on site and free wood chips from arborists are a great resource for not only protecting your plants but for building healthy soil at the same time.

If snow or ice accumulates on your plants, let it melt off on its own. Removing snow can cause branches to snap back abruptly, thereby damaging the circulatory system of the plant. Snow actually has an insulating effect on plants when we encounter frigid night time temperatures. Vertical branching conifers are an exception to this advice. Many of these types of plants will bend with the weight of our heavy snows but not bounce back once the snow is gone. In this situation it is important to knock heavy snows off to allow the branches to revert to their normal position. An example of one of these plants is the ubiquitous Thuja occidentalis ‘Pyramidalis’ also called Arborvitae, seen used as screens and living fences in many northwest yards. 

If a tree becomes uprooted, sometimes it can be saved if at least one third of the root system is still in the ground. Do this when the temperatures have warmed up. Prune broken branches now to avoid further tearing, but wait until spring to determine if branches are indeed dead.  Pruning out live wood, especially in early spring, can further stress the tree.

Salt damage can cause twig dieback and early fall coloration. Buds and small twigs of some plant species become more prone to freezing and may be slow or fail to open in the spring. Salts can also absorb water making it unavailable to roots and thus dehydrating the plant. Be judicious when applying salt to pathways to avoid damaging your plants.

If the buds of spring bloomers have been damaged, you will get fewer flowers this year. Leaves of broadleaf evergreens often droop during cold weather, but will uncurl when it warms up. Brown leaves can be due to sun and/or wind damage; wait until mid-spring before pruning out injured foliage 

Some plants, especially those in containers, may sustain root damage (roots look blackish and are often soft) because they are not as protected as plants planted directly into the soil. They might leaf out in the spring but will then wither and die. Protect potted plants by making sure the soil is well watered and the plant hydrated. Move more tender varieties to sheltered areas, being aware of the possible need to water if you are sheltering on a porch or near the house. Smaller pots can be heeled into a mulch pile in the yard for insulation or wrapped with insulating materials to protect the root system.

Sun scald is another problem, especially for trees that have been newly planted or those with smooth or thin bark. Wrap the trunk with a light-colored covering, keeping it on through the winter and into the first growing season. If a fruit tree has been damaged, remove developing fruits to prevent further stress on the tree. Monitor for signs and symptoms of insect damage. 

Frozen lawns are susceptible to damage if there is a lot of foot traffic on them. Avoid walking across the lawn during frigid weather if possible. Don’t plan renovation work until early spring to avoid periods of cold weather when the lawn will be under stress.

If you sustain winter damage on your plants make sure that they then receive adequate water through spring, summer and fall. Mulch liberally; fertilize as needed, avoiding excess soluble nitrogen fertilizer. Slightly decrease water in September to encourage hardening off, but water thoroughly in October until we get a freeze. It is important for plants to be adequately hydrated when entering cold temperature extremes.

If a tree loses more than half of its branches, it may not be worth saving. If bark has been ripped, woody plants are at risk of sunscald or decay. If you need to replace a damaged tree, consider replacements that will withstand the effects of severe winter weather. Conical shaped trees and those with more horizontal branching sustain the least amount of damage. Slow growing trees (their wood is not as brittle) and those with wide branch crotches also fare better. 

For future garden planning, take care to site your new plants well. Tall trees should be planted far from utility lines. Site broadleaf evergreens that easily succumb to winter damage in areas where they are protected from both winter wind and sun. These include daphne, camellia, azalea, and rhododendron. Do not let them dry out, especially as fall wanes and we enter winter cold spells; protect the roots of immature shrubs with extra mulch or burlap.  Avoid planting in areas that maintain winter wet or that will be in the path of falling snow or ice. Avoid planting under the eaves of houses unless you plan to water through the winter.