Where I live in the northeast the ground is just about frozen. This is my cue to protect the plants in my garden that have shallow roots. This includes any new plants that have not had a full season to get established.
Why now? The purpose of winter mulching is to keep the ground around these plants consistently frozen. Without protection the cycle of freezing and thawing which occurs throughout the season in my USDA Zone 5 garden can cause plants to heave out of the ground and expose their roots to the biting cold and wind.
In addition to newly planted plants, some shallow rooted plants are particularly prone to heaving, according to my friend the horticulturist Ruth Clausen. Included in this group are members of the coral bell clan—heucheras, heucherellas and tiarellas. Heucheras (shown) have become so popular in recent years, and indeed I have lost several to heaving. I am determined not to let that happen this winter.
What Qualifies as Winter Mulch? The best "mulch" for your plants is snow, because it keeps the ground consistently frozen and it disappears in the spring, allowing plants to gradually come out of dormancy as temperatures begin to rise. In most parts of the country, however, there is no guarantee the ground will be covered in snow all winter.
Evergreen Boughs. I use evergreen boughs to protect my garden beds. We always gather greens from the farm where we get our Christmas tree. We’ve noticed that people cut down their tree and leave behind lower branches and other greens, so we sweep them up and bring them home (no charge). Now that the holidays are over, we can cut the branches off our own tree and use those too. I’ve also noticed greens along the side of roads (mostly white pine) that dropped during the infamous Halloween snowstorm in the Northeast. Most of those are good for the taking too.
The advantage of evergreen boughs layered on your garden bed is that they are easy to gather up in the spring when temperatures begin to rise. Also, they do not provide a haven for burrowing voles and mice the way leaves or shredded bark can. And they really do shield your plants from the sun, which is what causes thawing. Evergreen boughs can be prickly to handle, so be sure to wear gloves.
Dorian Winslow is the president of Womanswork, and is passionate about making the best products on the market for women who garden and work outdoors.
Horticulture publishes the free weekly e-newsletter, "Smart Gardening Tips," and "The Curious Gardener," a free monthly e-newsletter with more tips and articles by Dorian. Subscribe to our e-newsletters and receive a free gift.
Learn all about mulch with Mulch It! A Practical Guide to Using Mulch in the Garden and Landscape.
Watch and listen to a slideshow presentation on "Year-Round Garden Maintenance."
Get the most out of your vegetable garden with Four-Season Harvest, Organic Vegetables from Your Home Garden All Year Long, by Maine-based Eliot Coleman.