Winter Injury

Winter damage to trees can be divided into three categories: cold injury, desiccation, and salt injury. The most common damage is due to extreme cold. Low temperatures can damage or kill plants not adapted to survive them.

A tree’s ability to withstand low temperatures is not static. Plants increase in hardiness during the late fall and early winter. As spring approaches, hardiness begins to wane as plants prepare for the onset of active growth. That’s why sudden extreme low temperatures in early spring are so damaging.

Desiccation, or winter burn, occurs when sun and wind cause water loss in leaves and the needles of evergreens. Symptoms include marginal browning of leaves and needles, or in severe cases, leaf death. Desiccation occurs most often in late winter when sunlight intensity increases.

Injury from de-icing salt is always a concern for plants located along sidewalks and roadways. Plants even hundreds of feet away from heavily traveled roads commonly suffer from salt spray damage. Salt injury to evergreens, especially white pine, often becomes apparent in late winter. Salt accumulating in the soil is usually more damaging to plants than foliage burn. High salt concentrations cause reverse osmosis; meaning water actually flows out of plant roots into the soil. Plants quickly dry out and die.

Plants that have suffered winter damage need special care. To insure optimal growth, plants should be watered, properly mulched, and fertilized. In cases of cold injury, pruning should be delayed until the extent of the damage is evident.

How can winter injury be minimized in the future? Make sure the plants are adapted to their site. For example, if a plant is too tender for a sunny southwest exposure, relocate it to a more protected location. See that plants are well watered and mulched entering the winter. A study by the University of Massachusetts suggests moisture levels in September are especially critical. Protect plants with burlap, evergreen boughs, or have Hartney Greymont apply a transparent film called anti-desiccant. These measures will help plants conserve water, and remain healthy and attractive during difficult winters.