Winter Protection for Plants

Winter is a perilous time for garden plants, but damage isn't caused by low temperatures alone — leaves become scorched if plants can't obtain enough moisture, sudden temperature changes can cause the bark on trees and shrubs to split, and alternate freezing and thawing can break plant roots.

The key to protecting your garden from cold and frost damage is good planning. If you think you'll need mulches or other protective devices, get them ready in the fall.

Cold Damage

Extreme cold damages some plants, so choose plants that are not usually damaged by cold in your area. You can grow tender exotics almost anywhere with enough attention, but the extensive care needed may not be worth the extra trouble.

After the first hard freeze in the fall, untie plants that are trained up on supports or trellises, lay them on the ground, and cover with mulch. If a shrub (such as a rose) can't be bent over to lie on the ground, dig up the roots on one side, tip the plant over, and cover it with soil or heavy mulch.

Shovel snow onto short plants as an insulating cover. Build wire cages around taller plants and fill them with snow, straw, or dead leaves for insulation.

Spongy plastic fabric is an excellent insulating material. Cover plants with it, or use it inside a wire cage for extra insulation. It is susceptible to deterioration from ultraviolet radiation, however, so apply an additional white plastic covering on plants in full sun.

Winter Scorch

What many people assume to be frost damage on trees and shrubs is often actually scorch, which is caused by a lack of available water when the soil is frozen and cannot yield water. Wind on a sunny winter day is especially damaging to plants, because plants can't replace the moisture lost through their leaves.

Give plants a thorough watering in the fall, so that the soil is moist when it freezes. Mulching the ground around plants reduces soil freezing and makes it easier for roots to continue functioning during cold weather. Shade plants during the winter with snow fencing, lath, or other covers.

Frost Heaving

Cycles of alternate freezing and thawing of soil can cause plants to be shoved out of the ground, breaking and exposing some of the roots — a phenomenon known as heaving. Small, shallow-rooted plants are particularly susceptible to heaving.

After the ground is frozen, mulch plants with straw or sawdust to keep the soil from thawing until spring. If a plant has heaved, keep it covered and frozen until spring approaches, then work the ground to permit replanting.

Snow Damage

The weight of excessive snow on branches can break or deform plants. Protect small plants with boards leaning teepee-fashion over them. You can tie spreading shrubs, such as boxwood, into shape with twine in the fall so the weight of the snow open and deform them. Shake or sweep snow and ice off limbs that are near the breaking point.

Salt Injury

When road salt lands on leaves or is absorbed through roots, it causes browning on the side of the plant that faces the road. New growth in the spring will be normal, but stunting and eventual death will occur if salt accumulates in the soil.

Protect street-side plants from salty water and slush with a wrap or screen of burlap or plastic. Leach excess salts from the soil in the spring with long irrigations, unless spring rains are heavy.

Republished with permission from The Scotts Company, www.scotts.com.
Copyright 2008 The Scotts Company, LLC. All Rights Reserved.