Winter mulching as the ground begins to freeze

By Linda C. DOLAK

OSU Ext. master gardener volunteer

Many gardeners feel mulching the garden is done only in the spring or summer.

It definitely adds to the beauty of the landscaping, and it helps to keep your plants, trees and shrubs moist.

However, when temperatures drop and freeze, and frost begins, we need to throw an extra blanket on the plants, just as we do to our beds.

Mulch prevents drastic changes in soil temperature.

Mulching in the winter is one of the best lines of defense against the chilling weather.

This protective layer is not necessarily only for warmth, but is meant to prevent alternating freezing and thawing which causes “heaving” of plants out of the ground.

This process can injure the plant roots and push the plants and bulbs up out of the soil.

Mulching is meant to keep the plants dormant (inactive) during winter months

Do not mulch too soon. Mulching too early gives mice and other rodents a comfy place to build nests. It should be done after the ground begins to freeze, but before the first snow.

Apply at least 3 to 4 inches around each plant, then gently pull the mulch away from the trunks and stems to allow the plants room to breathe.

Exceptions to mulching would be to roses and strawberries.

Mulching of rose bushes is meant to protect, and should be applied to the graft union where the flowering part is grafted onto rootstock.

If this protective step is not taken, the top of the rose bush may die.

Strawberries need the mulch to protect the flower buds that will become next year’s fruit.

The buds will not survive temperatures below 15 to 20 degrees.

Mulch them after the plants have stopped growing because mulching before this can actually smother the crowns.

And strawberries need to be uncovered as soon as they begin to grow in the spring.

There are many materials that can be used for mulch, such as straw, cornstalks, sawdust and shredded or chipped bark.

Also, chopped leaves and compost are good because they insulate the beds.

However, perennials and bulbs can push up through the compost in the spring.

Bark mulch is commonly used around trees and shrubs.

A tree is properly mulched over the root zone, but not up against the trunk.

Mulch against the trunk provides good cover for mice and allows them to gnaw on the bark which will “girdle” (choke) the plant.

Mulch that has been volcanoed, or piled high (in a tepee manner), may look nice, but can actually suffocate the tree.

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