How Snow and Ice Damage Trees and Shrubs

Heavy snow, ice, and freezing rain can cause significant mechanical and physiological damage to trees and shrubs, especially in regions that experience wet, heavy snow or ice storms. Here are the main ways damage occurs:

1. Branch Breakage from Weight

  • Wet snow and ice are much heavier than dry snow. A single inch of wet snow can weigh 5–20 pounds per square foot; ice can weigh even more (up to 1–2 pounds per square inch on branches).
  • Evergreen trees (pine, spruce, fir, cedar) and broadleaf trees with dense canopies hold more snow/ice, increasing the load.
  • Branches bend or snap under the weight, especially when snow accumulates on one side or during wind gusts.
  • Common victims: young trees, thin-branched species (birch, willow, poplar), and evergreens with flexible or brittle wood.

2. Stem and Trunk Splitting

  • Ice accumulation or heavy snow can cause the trunk or main stem to split (frost cracks or “ice splitting”).
  • Rapid freezing after a warm spell can also cause the bark to crack as sap freezes and expands inside the wood.
  • Trees with narrow branch angles (e.g., some maples, crabapples) are especially prone to splitting at the crotch.

3. Uprooting or Leaning

  • Shallow-rooted trees (e.g., silver maple, willow, spruce) or trees in saturated soil lose anchorage.
  • Heavy snow/ice load can tip the tree over, especially if roots are already weakened by decay or poor drainage.

4. Bark Damage and Sunscald

  • Ice can strip bark or cause it to crack when branches rub together.
  • After ice storms, exposed wood or bark can suffer sunscald (winter injury) when sunny winter days cause rapid temperature swings, damaging cambium tissue.

5. Dehydration and Winter Burn

  • Evergreens can suffer “winter burn” when frozen ground prevents roots from taking up water, but the needles continue to lose moisture through transpiration on sunny, windy days.
  • Ice-covered needles increase water loss and can lead to browning or needle drop.

6. Secondary Damage from Disease and Insects

  • Broken branches and torn bark create entry points for fungi (e.g., cytospora canker, wood decay fungi) and insects.
  • Damaged trees are more susceptible to pests in the following growing season.

Common Species Most Vulnerable

  • Evergreens: Norway spruce, white pine, Douglas fir, arborvitae, Colorado blue spruce
  • Deciduous: Silver maple, boxelder, river birch, willow, poplar, some fruit trees (apple, pear)

Prevention and Mitigation Tips

  • Prune properly in late winter/early spring to remove weak, narrow-angled, or overhanging branches.
  • Install support cables or braces on high-value trees with tight crotches.
  • Shake snow off branches gently with a broom or pole during storms (avoid shaking ice—it can cause more damage).
  • Avoid late-season fertilization (can promote soft new growth that’s easily damaged).
  • Mulch around the base to insulate roots and reduce freeze-thaw cycles.
  • Plant windbreaks or choose more resistant species in high-risk areas.

In severe ice storms or heavy wet snow events, some damage is unavoidable, but proactive pruning and proper tree selection can greatly reduce the risk and severity.