Key Takeaways
Evergreens most susceptible to winter burn include broadleaved plants like rhododendrons and holly.Mulching can help maintain soil moisture in the winter and prevent and bronzing burn.Use organic mulches like shredded bark or pine needles.
As their name suggests, evergreen trees and shrubs are known for maintaining their green foliage all year long and staying durable throughout winter, but that doesn’t mean they can skip winter care altogether.
Evergreen trees can experience winter burn, which causes leaves or needles to turn brown and can even kill branches or the entire plant.
“It happens because evergreen trees and shrubs continue to lose moisture through transpiration but are unable to replace the lost moisture from frozen ground,” explains Sandy Feather, an arboriculture expert and educator for Penn State Extension of Allegheny County.
You can protect evergreens in winter by installing wind breaks and protective barriers, keeping them well-watered, plus mulching around the base of the plants once the ground has frozen. But there are so many different types of trees and types of mulch, so we asked Feather for guidance on mulching evergreens during winter.
Meet the Expert
Sandy Feather is an educational programmer at Penn State Extension with expertise in arboriculture, native plants, organic land care, and pest management.
Why You Should Mulch Around Evergreens in Winter
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BlackBoxGuild / Getty Images
“Mulch acts as insulation and can reduce the impact of freeze and thaw cycles by maintaining a consistent soil temperature,” Feather says.
Mulching evergreens in winter can also help prevent frost heaving, an expansion of the soil that occurs during freeze-thaw cycles that can cause the roots of recently planted trees to emerge above the soil line.
Even in spring, a thick layer of mulch applied earlier in winter continues to benefit evergreens by keeping weeds down and protecting soil moisture.
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Evergreens That Will Benefit from Winter Mulching
Because they have large, flat leaves rather than thin, waxy needles, broadleaved evergreens are most susceptible to winter burn. More foliage surface area means more transpiration, especially in particularly harsh, dry, or windy conditions.
Protect these plants, which are commonly used as landscaping plants, hedges, and topiary plantings, in winter and beyond with a layer of mulch. Here are six types of evergreens that could benefit from mulching around the base this winter.
Boxwoods
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Marina Denisenko
You can protect boxwood shrubs (a broadleaf evergreen) from winter burn by spraying an anti-desiccant on the leaves, covering them with burlap, or mulching.
Boxwoods require organic mulch (like shredded bark or pine needles), but be careful not to over-mulch near the base, as that can attract pests that can also damage your plant.
Rhododendrons
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Volha Halkouskaya / Getty Images
If you live in a region with snowy winters, perennials like evergreens may actually benefit from being covered in snow. That’s because snow acts as a good insulator and protector for roots and can help maintain soil moisture.
If not, you can recreate this protection for rhododendrons, another broad-leaved evergreen susceptible to winter burn, by adding a couple of inches of mulch around the base of the plant. Organic mulches also work best here.
Holly
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Feifei Cui-Paoluzzo / Getty Images
With their glossy, dark leaves and bright red berries, holly trees are a quintessential winter evergreen shrub.
Protect holly by laying down a couple of inches of pine bark mulch or pine needles at the start of the winter season.
Contrary to popular belief, these mulches won’t acidify the soil to the pH levels that holly needs to thrive, but they’re great for insulating roots, holding in moisture, and keeping weeds down once the growing season starts in spring.
Azalea
A selling point of Stewartstonian azalea is its fall color, which, as you can see, makes it a “red azalea” on two scores.
Credit: David Beaulieu
Azalea bushes are another acid-loving broadleaved evergreen that can benefit from some winter protection to prevent leaves and branches from drying out.
Add 2 to 3 inches of organic mulch like pine bark nuggets, pine needles, or shredded leaves around the base of the shrub once the ground freezes to insulate its shallow roots.
Mountain Laurel
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dsnyder427 / Getty Images
These native broadleaved evergreens will put on a prettier show in spring if they’re protected from moisture loss in winter. Mountain laurel is another shallow-rooted shrub that benefits from mulching at the start of the cold season.
Since mountain laurel thrives in part-shade conditions, proper siting will also help protect it from harsh sunlight that can exacerbate moisture loss in winter.
Arborvitae
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Although broadleaved evergreens are at the greatest risk of winter burn, plants like arborvitae and juniper, which have scale-like leaves, and needled evergreens like firs, pines, and yews are also at risk.
In addition to mulching at the base of plantings once the ground freezes, you can protect them from dehydration by leaving snowfall in place on and around trees and shrubs.
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