What Is Winter Mulching of Plants?

Mulch is used by gardeners for a variety of purposes like weed control and soil moisture retention. As the seasons change, so changes the purpose of mulch and the types of plants that require mulching. Winter mulching is an excellent practice, particularly for gardeners in regions that experience freezing temperatures during winter months.

Many gardeners mulch around their plants in winter to protect plants and their roots from the detrimental effects of alternating freezing and thawing winter temperatures. Freeze and thaw cycles can cause the ground to heave roots upward, exposing them to harsh winter temperatures. Mulch serves as an insulator that keeps soil temperatures relatively even as air temperatures fluctuate. This protects shallowly planted bulbs, crowns and roots left in the ground. This also prevents dormant plants from breaking bud too early, by keeping soil temperatures cool during a warm spell.

Although mulch is commonly used in areas of the country where freezing temperatures are prevalent in winter, mulch can also be used in temperate climates where temperatures rarely drop below freezing. In these areas, gardeners often plant tropical species and tender perennials that die to the ground only to return in the spring. Mulch is used to help these warm-weather plants survive the winter.

Apply mulch to the soil around shrubs, but keep the mulch away from the trunks of trees and the stems of shrubs. Do not allow the mulch to come into direct contact with living tissues of the plant, since it can cause stem rot. Prune away the stems of plants that have died to the ground, and mulch directly over their roots or bulbs. A 2-inch layer of mulch is adequate. Apply in winter after the plant is dormant and when the weather has reached freezing temperatures several times.

Winter mulch is removed at the end of winter. Gardeners who have the means can compost their mulch. Plants that require mulch in the spring will benefit from a fresh layer of mulch spread over their roots when the winter mulch is removed. Mulch left on the ground from one season to the next will slowly disintegrate and can prevent young bulbs from sprouting.

Pine bark is a common mulch material used by many gardeners. It is readily available at garden centers and nurseries and is attractive as well as useful. Straw is another type of mulch that is used and is less expensive than pine bark. Straw breaks down quickly, must be replaced frequently and can contain weed seeds. Some gardeners use leaves from their own lawns as mulch, since leaves are a good insulator. However, leaves can mat down, preventing new growth in the spring as well as good air circulation. Partially shred the leaves and allow them to decompose somewhat before use.