⚠ Moderate Urgency

Cracks in Trees After Winter

Quick Navigation

What It Means Causes Trees Affected How Urgent What To Do Call an Arborist?Regional Notes Related Pests FAQ

What This Symptom Usually Means

Cracks that appear on tree trunks during or after winter are typically caused by frost cracks or sunscald. Frost cracks are vertical splits caused by rapid temperature changes — the south/southwest side of the trunk warms during the day, then sudden nighttime cold causes the bark and wood to contract and split. Sunscald kills bark on the sun-exposed side of young trees. Some cracks are cosmetic and the tree compartmentalizes them. Others reopen annually and can become entry points for decay. New cracks accompanied by leaning or root heaving are a safety concern.

Most Likely Causes

Frost cracks

Vertical splits on the south or southwest side of the trunk. Caused by differential thermal expansion and contraction. Often reopen each winter with an audible crack. More common on thin-barked species.

Sunscald

Bark death on the sun-exposed side of young trees. Winter sun warms bark tissue above freezing during the day, then tissues refreeze at night, killing them. Dead bark eventually cracks and peels.

Included bark / weak branch unions

Branch attachments with bark growing inward instead of outward form weak points that crack under ice, snow, or wind loads.

Pre-existing wounds reopening

Old wounds and cracks from previous injuries may reopen during winter freeze-thaw cycles as callus tissue is stressed.

Ice and snow loading

Heavy ice storms can crack branches and trunks. The damage may not be noticed until the ice melts.

Trees Commonly Affected

Maple

Thin bark makes young maples very susceptible to sunscald and frost cracks

Linden

Frost cracks are very common and often chronic

Oak

Young oaks are susceptible; mature oaks' thick bark provides better protection

London Plane/Sycamore

Exfoliating bark provides some natural protection

Cherry

Thin bark is highly vulnerable to sunscald damage

Honey Locust

Common frost crack victim in the Midwest

How Urgent Is This?

⚠ Moderate Urgency

Moderate. Most frost cracks and sunscald injuries are cosmetic and the tree compartmentalizes the damage. However, cracks that extend deep into the wood, gird more than a third of the trunk, or are accompanied by leaning require professional assessment. Chronic frost cracks that reopen annually create pathways for wood decay over time.

What You Can Do Right Now

For young trees: wrap trunks with commercial tree wrap or white trunk guards in late fall. Remove in spring.
For existing frost cracks: do not fill with caulk, foam, or cement. Let the tree compartmentalize naturally.
Check for secondary problems: is the crack oozing (bacterial wetwood)? Are insects using it as an entry point?
For included bark branch unions: monitor for cracking and consider cabling if the branch is large and over a target.
After ice storms: assess damage but do not rush to prune. Wait for spring to see what recovers.
Plant new trees with the graft union or most tender bark facing north/northeast to reduce sunscald exposure.

When to Call a Certified Arborist

Contact a certified arborist if any of these apply:

✓A crack extends through the trunk and the tree appears to be splitting apart
✓Cracking is accompanied by new leaning or root heaving
✓An ice storm has caused major branch or trunk damage
✓A chronic frost crack has developed significant internal decay visible through the crack
✓A large tree has an included bark union that is cracking and could fail

Find an Arborist Near You

State & Regional Differences

Midwest

Frost cracks are extremely common due to dramatic winter temperature swings. Wisconsin, Minnesota, and Michigan see the most frost crack damage. Young maples and lindens are frequent victims.

Southeast

Less common overall, but unexpected cold snaps can damage subtropical and warm-climate species that are not cold-adapted.

West

Sunscald is more common than frost cracks in arid western climates where clear winter skies create large day-night temperature differentials.

Northeast

Both frost cracks and ice damage are significant winter concerns. Winter storms can load trees with ice and snap branches or split trunks.

Frequently Asked Questions

Can a frost crack kill a tree?

A frost crack itself rarely kills a tree. Most trees compartmentalize the damage and continue to grow around it. The greater long-term risk is that chronic frost cracks create an entry point for wood-decay fungi. Over decades, internal decay can reduce the tree's structural integrity. Monitor chronic frost cracks for signs of advancing decay.

Should I fill a crack in my tree trunk?

No. Filling cracks with cement, foam, caulk, or other materials is no longer recommended. Research has shown that fillers can trap moisture, promote decay, and interfere with the tree's natural compartmentalization process. Leave the crack open and allow the tree to respond naturally.