How To Minimize Winter Injury To Trees And Shrubs

During the early months of fall, the slow decrease in day length and temperatures, increases your plants ability to handle cold temperatures.
In order to minimize winter injury to trees and shrubs, the factors most important, in how much injury or damage a plant receives from cold are:

  • How Cold It Gets
  • How Hardy It Is

However, other factors come into play a role in how much cold damage occurs.

Good Care Year Round Important

Make sure landscape plants receive good care throughout the growing season. Plants doing poorly from inadequate nutrition or weakened from insect damage or disease, find themselves more susceptible to cold injury.
winter tree prep

Avoid late season pruning and fertilizing of trees, shrubs and groundcovers, this can flush tender growth which is not cold-hardy.

However, depending on the tree, pruning can help Prevent Winter Tree Plant Injury.

Winter Sunscald

When is sunscald on trees most apt to occur? Are some trees more susceptible to it than others?

Sunscald is apt to be most severe in the late Winter or very early Spring on days when there is not enough breeze to disperse the hot rays of the sun that strike the bark of the tree.

Because of the heat of the sun the cells are more active and, therefore, more sensitive to the cold that follows after the sun has gone. Enough injury may kill the bark.

The southwest part of the tree gets the worst burn because the sun’s rays reach their greatest intensity at that part of the day. Among the trees more susceptible to sunscald are mountain ash and Norway maple. Boards or some other form of obstruction on the south and southwest sides of the trunk will provide protection.

On deciduous trees and shrubs, the tender bark on the side facing south warms quicker than the bark on the northern side, causing sap to flow even on the cold days. The sap rapidly refreezes temperatures drop suddenly, resulting in sunscald – the bark splits open from the ruptured plant cells.

Cold winds can cause alternate freezing and thawing of the bark and sap. This type of damage can be prevented by covering the trunks in the fall with wrap or burlap.

Evergreens are not as affected as deciduous trees by sunscald trunk damage due to the shade provided by their own foliage, but are very susceptible to desiccation caused by the drying effect of the wind and sun when water loss exceeds the uptake of water by the roots.

The use of anti-desiccants will give some protection from desiccation, as will protecting vulnerable plants with a windbreak of stakes and burlap.

Covering Plants – Does It Help?

Covering plants protects more from frost than from extreme cold. If they are not too large, individual plants can be protected with cardboard or Styrofoam boxes, or cloth such as sheets or landscape fabric.

Any covering should extend to the ground and not come in contact with plant foliage. Foliage in contact with covers can be injured due to the heat transfer from the foliage to the colder cover. Remove covers as soon as the temperatures begin to rise to prevent damage from trapped heat.

In northern regions, mulch can help protect plants from freeze-thaw cycles. It insulates the ground, reducing the heaving of plant crowns caused by the freeze-thaw cycle and moderate the soil temperature to prevent root damage. Mulch also holds snow acting as an insulator.

Proper plant selection, good landscape maintenance practices all year long, and a quick response when the weather forecast turns nasty can help prevent sudden weather changes during the fall and winter months from seriously affecting your landscape plants.

Tips To Improve Your Plant Care
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