Mulching in Winter

mulching junipers

Baby it’s getting cold outside! You’re heading in to cozy up by the fire, but your trees are not! In most managed landscapes, those trees won’t even have the benefit of a layer of fallen leaves to act as a winter coat protecting the soil.  With that in mind, winter is a good time to apply a fresh layer of mulch.

Why Mulching in Winter is Important

Mulch is highly effective practice for maintaining tree and shrub health with many benefits. During winter, mulch helps conserve soil moisture and moderate the soil temperature. Above all, this maintains a healthy environment for the root system. Further, it protects plants from fluctuating temperatures and the alternating freezing and thawing cycles common this time of year.

What Makes Good Mulch

Fresh woodchips, bark nuggets and composed leaves or pine needles make a desirable mix for mulching. Be careful to avoid woodchips from certain species that are allelopathic like redwood or walnut. Allelopathic plants produce biochemicals that are detrimental to other plants. There are some other important considerations. Do not mulch trees susceptible to insects that are attracted to fresh wounds with chips from the same species. Examples include pines in areas infested with pine bark beetles and oaks in areas with oak wilt. Also steer clear of any mixtures that contain plastic, stone, sawdust or grass clippings.

Tips for Applying Mulch

The best time to apply winter mulch is after the first hard freeze. When applying, mulch from near the trunk to the dripline. To clarify, this is the outermost edge of the tree’s canopy where water would drip from the tree onto the ground. If your mulch bed cannot be that large, make it as close as possible! Keep in mind that there is no requirement that the bed be round or symmetrical.  The mulch layer should be between two and four inches depending on the species. As old mulch decomposes, add more to maintain that depth. Near the trunk, it should taper down to a thin layer. Moreover, piling it against the trunk can actually be a big issue. This common practice is sometimes called volcano mulching and can harm trees.

Ultimately, mulching is one of the most beneficial, and simplest, things you can do for your trees and shrubs.

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