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University of Illinois Extension

Protect Landscape Plants from Winter Injury

December 26, 2012

Wind, sun and freezing temperatures take a toll on landscaping plants through the winter. Signs of winter injury include discolored cankers or sunscald on exposed limbs or at the trunk base, damage to the taproot and side roots and injury to leaf and flower buds. In some cases, homeowners will see blackened sapwood and death of the entire plant.

Frost cracks are the most common signs of winter injury. Frost cracks are vertical separations of bark and wood on the south or southwest sides of a trunk. The cracks may extend to the center of a tree and cause it to break apart under the weight of snow or ice.

Young, thin-barked trees can be protected from frost cracks by wrapping the trunks with sisal-kraft paper, strips of burlap or aluminum foil. A coat of whitewash or a 6-inch board tied upright on the south-southwest side of the trunk can also work.

Trees subject to frost crack, if planted in exposed locations, include apple, ash, beech, elm, horsechestnut, linden, London plane, maple, oak, poplar, sycamore, tulip tree, walnut and willow.

Boxwood, junipers, yews and other multiple-stemmed evergreens that tend to develop frost cracks can spread, split apart and break under a load of ice or snow. Protect these trees by tying the branches together with strong cord.

Some plants, such as evergreens, should be protected from winter sun and drying winds. Barriers made of canvas, plastic, cheesecloth, burlap or slat screens placed two feet away on the south or southwest sides are effective screens. Put 2 to 6 inches of organic mulch over evergreen roots, around roses and over fruit tree roots to prevent deep freezing. The mulch also protects against alternate thawing and freezing which can shear off feeder roots.

Several products are available to protect broadleaf and other evergreens from winter leaf burn. These include a "no wilt" latex and plastic anti-transparent sprays. These products should be applied to foliage in late fall and again during mid-winter when the temperature is above 40 F.

Source: David J. Robson, Extension Specialist, Pesticide Safety, drobson@illinois.edu

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