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Protect your trees, shrubs this winter page 2
Take steps now to help your plants avoid injury from winter weather

Date published: 11/16/2012

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Shade and windbreaks can also provide protection. Plants that freeze and thaw slowly are less prone to injury. Plants can be protected by building frames over the plants and covering the frames with burlap. The covering material should not touch the plants because contact between the leaves and the covering can accelerate leaf heat loss. Windbreaks can be built by attaching burlap or canvas to a two- sided frame.

Injury from freezing takes two forms. Bud growth that in stimulated by late summer or fall fertilization is prone to freeze damage because young buds have not had enough time to harden off prior to cold weather. Ice crystals that form within these buds rupture cell walls.

Discolored leaves and dead branch tips are signs of this damage, which can be prevented by delaying fertilization until after the plant is dormant.

The other is "southwest injury" or frost crack injury. This is caused by sharp temperature changes that can freeze water within the trunk or branches causing splits called frost cracks. Mild frost crack injuries may appear to close when warm weather occurs, but the damaged wood fiber may not grow back together.

The term "southwest injury" comes from the fact that the southwest side of young plants is more prone to the damage because the warmth of the afternoon sun creates further extremes between day- and nighttime temperatures.

Damaged branches and areas can be pruned out of the injured plants in the spring. Damaged plants may be delayed in starting new growth, so wait to wait until after new spring growth starts to assess the damage. Broadleaf evergreens with leaf injury can start growing new leaves if the branches and leaf buds have not been too severely damaged.


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John E. Howe is an agent in Virginia Cooperative Extension's Spotsylvania County office specializing in animal science. Phone 540/507-7571; email jhowe@vt.edu.