University of Maryland Extension

Winter Damage (Burn)

boxwood buried in snow
Snow covered shrub

Key Points  

Winter damage or winter burn occurs during the winter or early spring. It can result from exposure to drying winter winds, low temperatures, late frost, or freezes. Often the damage is cosmetic and the leaves drop off or new growth in the spring masks the damage. Sometimes pruning is necessary to remove brown, dead, or broken stems or branches. 

Leaf Scorch 

  • Symptoms are most severe on shallow rooted evergreens such as azaleas, rhododendrons, holly, cherry laurel, liriope, boxwood, and mountain laurel. 

  • Sometimes newly planted white pine and spruce can suffer needle scorch during their first season from limited root systems.

  • Needled evergreens in exposed conditions such as along roadsides and parking lots can suffer needle scorch.

  • Other plants prone to leaf scorch and winter injury include those at their northern limit for winter hardiness. These include southern magnolia, crape myrtle, aucuba, hardy gardenia, and camellia.

  • Injury can occur on dry, windy, warm, or sunny winter days when the ground is frozen.  Plants are unable to move water from the frozen soil to replace the water being lost from the exposed leaves. Leaves curl and droop, then brown from the tips and margins, giving them a scorched appearance.

  • Some plants, especially rhododendrons, try and cope by rolling their leaves to minimize leaf surface exposure.

  • Most damage is during the winter but in some cases, symptoms can occur during the spring as new growth appears. 

winter scorch on hardy gardenia
Hardy Gardenia with winter scorch

magnolia with scorched leaves
Magnolia with winter scorch

Salt Injury

  • Heavy accumulations of deicing salts from surface applications or airborne spray, especially along roadsides or sidewalks can cause leaf and needle scorch and may kill buds and branch terminals. 

  • Damage is caused by desiccation (extreme dryness) of the more tender tissue in buds and new growth.

  • Salt can also accumulate in the soil and cause root death from desiccation of root tissue.

  • Deicing salt runoff from one sidewalk or parking lot may not cause problems, but the combined effect from numerous such events raises the harmful concentrations of salt in adjacent soil and bodies of water.

yews damaged from deicing salt
Yews damaged along a sidewalk from deicing salts

junipers covered in deicing salt
Junipers in a landscape covered in deicing salts

Blighting or Browning of New Growth 

  • Warm temperatures in protected areas in February and March may stimulate buds, flowers, or shoots into growth too early.

  • Subsequent cold weather and frosts will kill young buds and tender new growth resulting in fewer flowers and later leaf development.

  • Frozen tissue damage frequently appears as blackened buds and leaves that may also drop off.

  • Pruning out remaining bare branches will help stimulate new growth later in the spring.

damaged, frozen branch
Frost or freeze damaged new growth

Blasted or Damaged Blooms

  • This damage results when flower buds swell and then freeze during cold snaps or late frosts. Star magnolia and lilac flowers frequently suffer from this type of injury.

damaged magolia blooms from frost
Blasted magnolia blooms

Branch Dieback and Leaf Yellowing

  • These symptoms occur from sunscald, frost cracks, root damage, and cold weather following a warm spell.

  • Frost cracks can occur during the winter on exposed bark, usually on the south side of a trunk or limb, where warming and subsequent rapid cooling causes expansion and contraction of tissues resulting in cracks.

  • These cracks can lead to damage of the vascular system and eventually disease cankers. 

Ice and Snow Damage

  • Symptoms include bent or broken branches from the heavyweight of the ice or snow.

  • Heavy snow can be gently knocked from branches, but ice-overed branches may actually be more brittle and suffer further damage if removal is attempted.

  • Wind during ice storms will cause the most damage.

  • White pines in our area are especially prone to winter ice and wind damage.

boxwood covered in snow
Snow-covered boxwood

Winter Color of Evergreens 

  • Symptoms of “winter color” can include gray, yellow, blue, purple, bluish-green, brown, and bronze leaves or needles.
    • Examples include
        1) Japanese cedar (Cryptomeria) turn bronze
        2) Yew (Taxus buccata) turn brown
        3) Eastern red cedar (Juniperus virginiana) turn brown
        4) Arborvitae turn brown
        5) Creeping juniper (Juniperus horizontalis) turn purple
        6) White pines (Pinus strobus) turn yellow
        7) Boxwood turn yellow-orange

      yellowish orange winter color of boxwood
      Winter color of boxwood

  • Some evergreens such as Leyland cypress and spruce usually don’t change color, but dieback in Leyland cypresses can occur under extreme winter temperature fluctuations.

    winter damaged Leyland cypress
    Severe winter damage on Leyland cypress
  • Causes of  ‘winter color’ can include low temperatures and drought stress. Often, the foliage colors will revert back to normal when springtime temperatures return to normal.

Management Strategies

  • Cultural practices, like mulching and adding compost to soil, that conserve soil moisture, prevent root damage and promote “hardening off” (physiological changes that prepare plants for winter temperatures) will help to reduce winter damage.

  • Avoid later summer fertilization and pruning as this stimulates late-season growth that does not have time to “harden off” properly and is more prone to winter injury.

  • When watering in fall, soak the soil several inches deep and then allow it to dry between waterings.

  • Freshwater sprays on foliage and deep watering in early spring will also help wash deicing salts from the leaves or needles and flush salts through the root zone faster to help reduce desiccation damage.

  • Deep watering will also encourage deeper rooting during the growing season which will help reduce damage from moderately dry periods and frozen soil.

  • Wait until the plant puts out new growth in the spring and assess the damage.

  • Typically, damaged leaves fall off or are masked by new growth. Severely damaged shrubs may benefit from pruning. Prune to remove dead, damaged or broken branches and to stimulate new growth.

Additional Resource

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Rev. 2019

 

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