Mulching for Winter

Mulching flowerbeds and plants for the winter slows temperature changes and water loss by creating insulation. We don't want to, nor can we, prevent the ground from freezing because the ice can actually be a good insulator. We simply want to prevent the ground from drying out and dropping too much below 32 degrees.

The type of materials used is important so we can make certain that there is enough air space. Since it's the dead air sapce that provides the insulation- just like layering your clothes on a frigid day- wood and bark materials are, in general, a much better mulching material than soil, and I have found them easier to handle.

Now, I know a lot of you use leaves. While this is not a terrible idea, it's not as beneficial as you might think. In the woods, leaves are part of a combination of sticks and twigs which animals work through and this prevents the leaves from becoming mashed down and, hence, allow air to circulate. In your yard, leaves can become so compacted that they can suffocate plants. Mixed into a combination with wood chips, however, they can be very helpful.

Our goal in most beds is 2 to 4 inches of a light porous material. Around shrubs and perennials that were mulched in the spring, rake lightly through the bed to fluff up what's there and add more wood chips to a depth of 2 to 4 inches.

We need enough to insulate, but more than 4 inches could prevent water and air from getting to the roots.

Mulching roses is a different story, however. Roots are generally winter-hardy; we need to protect the stems. Contrary to what you might have done in the past, don't trim your roses now. Pruning now might stimulate growth and a little extra length will help in piling the mulch around the bush and holding it there. I like to use shredded bark or wood chips because they allow good aeration, yet insulate all winter. We need to add something that lofts up, holding air space and preventing suffocation. Build a pyramid around, up and over the rose bush. Don't gry to cover the full height- it's difficult and really unnecessary. If stems seem dead in the spring, you can trim them then. Make the pyramid of mulch about 18 inches high. It will settle slightly, and that's fine. It's still high enough to protect the delicate bottom portions of the stems so we'll have enough to trim back to in the spring, but aerated enough to prevent suffocation.

You should mulch your vegetable garden, too. First, spade up the garden so that the soil is prepared for spring planting. Then, cover and add about 4 to 6 inches of this blend around plants or over barren garden soil. In the spring, as you begin planting your early vegetables, simply spade the leaves under or rake them aside and add them to your compost pile. I like to rake aside just what I need to plant, leaving the rest there until I plant my next vegetable and need more room. If you have the option, oak leaves will maintain their curled shape and not pack down as tightly. Their slight acidic nature is also very good around azaleas and rhododendrons.

Protecting our plants in the winter from abrupt temperature changes, or freezing while dry, can keep them healthier, and encourage spring and summer growth. But, remember, when mulching that more is not better. Like the air between the feathers in a down jacket, air between mulch particles keeps our plants insulated against extreme or rapid changes. However, more than 6 inches of very loose or 3 inches of more dense mulch is too much. It is also good, when possible to control, not to have any mulch up against the stems or trunks of plants.