Winter mulching protects your plants

By Hugh Earnhart

OSU Extension Master Gardener Volunteer

Mulches not only have a beneficial effect upon plant growth, but also reduce the time and labor required for garden maintenance. On a well-managed home landscape, mulching is a year-round operation.

In northern zones, winter mulch serves several important functions in the garden. It protects plants from severe cold, and the foliage of some plants from the effects of drying winds and winter sunshine, which are apt to sear and scorch tender growth. It also prevents plants from starting into growth too early in the spring. And, perhaps most important of all, it prevents the alternate freezing and thawing of the soil, which is so harmful to many herbaceous plants and can heave plant crowns out of the soil, leaving the roots exposed, resulting in more winter-killing than low temperatures.

A number of materials may be used as winter mulches, such as weed-free hay and straw.

If small evergreen boughs are available, they offer excellent material for winter covering. Aside from good air circulation, boughs may also be used to hold down leaves, straw and other light materials.

Fallen leaves are nature’s own covering. But if used for mulching, select leaves that will not mat down and become a soggy mat in the spring.

Leaves from oak, beech and sycamore trees are excellent, while maple, elm and other hardwood tree leaves should not be used unless they have been chopped finely.

Winter mulch should not be applied until the plants are completely dormant and the ground is frozen.

The benefit of the mulch is not only protection against cold, but also to protect the plants from thawing or freezing again in early spring.

The depth of winter mulch will depend on the material used and the severity of the winter. It’s as disastrous to apply too heavy a mulch and smother the plants as it is to apply too light of a covering. In the average winter, 2-3 inches worked into the roots should be adequate.

Removal of winter mulch should be done gradually, and the final covering should, if possible, be lifted off on a cloudy day so any young tender shoots that have started to sprout are not exposed to brilliant sunshine.

If you leave winter mulch on too late in the spring, it will seriously stunt the growth of the plants and inhibit new growth. It is usually safe to begin to remove the mulch when crocus bloom.

For additional information, see http://go.osu.edu/wintermulch. To learn more about options for the leaves in your yard, see http://go.osu.edu/leafoptions.