November 14, 2001
Stillwater Gazette
Betsy Halden

Mulches for winter plant protection

As I write this, we have another day of glorious fall weather. The clear blue skies, warm temperatures, sunshine tempt us to forget that soon real winter may arrive. Until that happens there are still garden chores to attend to. I have bulbs I would like to get in. And I have straw ready to use as a winter mulch.

Many gardeners recognize the importance of applying a winter mulch. Others think of mulching only during the growing season Not only do mulches aid in weed control and conservation of soil moisture, they provide much needed winter protection for shallow-rooted plants. Mulches can prevent rapid temperature fluctuations in the soil, therefore reducing the chances of winter damage to the plants.

Wait until the soil has been subjected to a few frosts or light freezes to apply a good mulch. The soil’s own warmth up to this point keeps the danger of freezing away from the plants. Once the soil begins to cool (you may even see ice crystals forming), go ahead and apply the mulch.

A good mulch consists of three to four inches of a coarse structured material. This type of mulch decomposes slowly and provides protection as it decomposes. Examples of a good mulch are shredded bark or straw. Stone or brick chips do not decompose or enrich the soil. Many gardeners avoid using leaves because the leaves have a tendency to mat when they get wet. At times this can cause suffocation to plant roots. However, oak leaves seem to hold their shape, and many gardeners prefer to use oak leaves as a winter mulch.

If you do not get mulch on your garden before the snow comes, do not worry. It is not likely you will lose all of your plants. As long as we have several inches of snow on the ground the snow will help to insulate the plant roots. When the sun starts to melt the snow later in winter then it is time to make sure the plants are insulated. As the snow and the ground melt, the soil starts to heave, possibly exposing tender roots. A good mulch will prevent the temperature fluctuations in the soil.

Betsy Halden is a Master Gardener with the University of Minnesota Extension Service. University of Minnesota Extension Service materials were consulted in the preparation of this column. You can reach Betsy Halden at eahalden@comcast.net