Winter weather is rough on shrubs. Protecting shrubs in winter involves insulating the roots and guarding the stems and branches from exposure to the elements. It’s important to understand the basics for protecting shrubs during winter to prevent damage resulting from cold weather, ice, and snow.
Winter Hazards for Shrubs
Shrubs go dormant in winter. During dormancy, a plant stops producing new growth, forms hard shells around buds, and uses stored carbohydrates to lower the freezing point of its internal water. Dormancy partially protects shrubs against winter weather, but not entirely.
Causes of shrub damage in winter include:
- Cold temperatures cause frost damage or winter branch dieback, especially if new growth is present during early-season or late-season frost.
- Heavy snow weighs down branches, causing bending or breaking.
- Wind causes water loss and dehydration, especially in evergreen shrubs in winter.
- Sunscald occurs when intense sun stimulates cell growth which is then killed if the temperature rapidly drops.
- De-icing salt accumulates in the soil, causing dehydration and impairing nutrient intake.
Three Strategies for Preventing Winter Shrub Damage
Here are a few strategies for protecting shrubs against the winter hazards described above.
1. Species Selection and Siting for Shrubs
Caring for shrubs begins with choosing appropriate species for your region and planting them in spots where they’ll have the best odds of success. To choose shrubs that grow well in your area, find out what hardiness zone you’re in. Only buy plants that are considered hardy (cold tolerant) in your zone.
After species selection, the next consideration is choosing an appropriate planting location. Shrubs in fully-exposed sites are more vulnerable to damage from snow, wind, and sun. Exposed shrubs may require more protective care.
Additionally, note that damage is most likely on the side of a shrub or tree that faces the sun or wind. In North America, the north, northeast, and east sides of buildings are better-protected against sun and wind.
Because shrubs are used as privacy screens or borders, they’re often exposed to the elements. In exposed locations, it’s important to choose cold hardy shrubs and to take protective measures to help them avoid winter damage.
2. Protect a Shrub’s Soil and Roots with Mulch
Freezing and thawing causes soil to contract and expand, which can damage roots. Meanwhile, soil loses moisture during winter. Both of these concerns are addressed with mulching. A layer of mulch helps soil maintain a consistent temperature while conserving water and nutrients.
Good winter mulch materials include:
- Straw or hay
- Shredded bark
- Shredded leaves
- Pine needles
- Compost
Apply mulch soon after the year’s first frost. Remember, the goal is to maintain a consistent soil temperature, not to keep the soil warm.
If it hasn’t rained recently, water the shrub before mulching. Then, apply a 2–3-inch (5–7 cm) layer of mulch that extends three feet (90 cm) from the stem. Don’t build a “mulch volcano” that climbs up the stem. Those invite pests. Instead, create a donut shape by leaving a mulch-free zone that extends six inches (15 cm) from the stem.
3. Use Wrapping to Protect Stems and Branches
Wrapping sensitive shrubs protects them from wind, frost, and snow. Wrap shrubs around the same time you mulch them—after the first frost but before the arrival of the season’s lowest temperatures.
Covering shrubs in winter includes:
- Covering stems to prevent sunscald and frost damage.
- Covering branches and foliage to prevent freezing windburn and snow accumulation.
Wrapping Stems for Winter Protection
Wrap stems or trunks using a product made specifically for that purpose, sold as “tree wrap” or “tree guard.” The material should be white so that it doesn’t absorb sunlight. If the shrub has a wide bundle of stems, bind them together with twine to make wrapping easier.
Wrapping Shrubs in Winter
You can fully wrap shrubs in burlap to shield the branches and foliage from wind and snow. Burlap is tough and breathable. However, wrap with caution to avoid these problems:
- Wrapping too tightly restricts airflow and breaks branches.
- Wrapping that creates a flat surface will collect snow and put pressure on the shrub.
- Wrap that’s left on during rain will soak the branches and lead to fungal growth.
- Pruning before wrapping may stimulate growth during the wrong time of year.
If you choose to wrap a shrub, create a pointed top to avoid snow accumulation. Only wrap shrubs that are dry (to avoid trapping moisture) and don’t pull the wrapping tightly around the branches.
If your main goal is to protect against windburn, creating a windshield using stakes and burlap or tarp may be more beneficial than wrapping.
Which Shrubs Are Most Sensitive to Winter Weather
When selecting a shrub, or any plant, the first factor to consider is its hardiness. If a shrub is listed as hardy in your zone, then it’s generally considered to be well-suited for the local climate.
Deciduous shrubs enter deep dormancy for winter protection. Popular deciduous shrubs that require minimal winter maintenance include hydrangea, dogwood, spirea, and forsythia. Note that cold hardy deciduous shrubs are still prone to winter dieback, especially if new bud growth is present.
Remember that cold hardiness is relative, based on the region. A shrub species’ hardiness may also vary from one variety to the next.
Broadleaf evergreens are shrubs or trees that maintain large green leaves throughout the year. While many evergreens are cold hardy, their foliage may dry out and turn brown when exposed to winter wind. Evergreens that may need extra protection in winter include boxwood, rhododendrons, arborvitae, and yew.
Use the methods described above to protect evergreens, shrubs at the edge of their hardiness range, or other sensitive shrubs in winter. It can also be helpful to gently remove heavy accumulations of snow on the foliage of evergreens. You can use a broom to carefully brush off snow or a more unconventional method is to use a leaf blower. You can blow off light weight snow cover to prevent heavy accumulations that can break branches.
Another Option for Overwintering: Growing Shrubs in Containers
If your local winters are harsh but you have room in your garage for a few large pots, you can grow small trees or shrubs in containers. Moving indoors for the winter, even to an unheated space, provides adequate protection for many shrubs. See our article to learn about 12 suggestions for Trees for Pots.
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