Tree trunk cracks can be alarming, but not every one means you need to remove your tree. Some tree bark splitting is a natural response to changing temperatures or growth, while other cracks may indicate structural weakness, decay, or storm damage.
Throughout Massachusetts and New England, freeze-thaw cycles, summer drought, and severe weather can all contribute to cracked tree trunks. Knowing the difference between a cosmetic bark split and a structural defect can help homeowners make informed decisions before winter storms arrive.
What Causes Bark to Split on Trees?
Tree trunks can crack for several biological, mechanical, and environmental reasons, including:
Frost Cracks – Frost cracks on trees result from rapid temperature changes in late fall and winter. They are common on young and thin-barked trees, such as maple, beech, linden, white pines, and fruit trees. This differs from sunscald, which can occur on the bark of trees facing south or southwest on sunny winter or early spring days.
Growth Cracks/Platy Trunk – Trunks can become platy or develop growth cracks when they grow faster than the outer bark can expand. Some species, like shagbark hickory and silver maple, naturally have platy trunks. These are often superficial cracks that don’t cause any significant structural damage.
Storm Damage – High winds, heavy snow or ice, and lightning strikes can crack tree trunks. Trees in open landscapes, along roadsides, or in exposed coastal locations may be more susceptible to weather-related trunk injury and temperature fluctuations.
Mechanical Injury – Impact from lawn equipment, vehicles, and construction activities can break the outer bark and cause open wounds that allow decay to progress.
Included Bark & Weak Branch Unions – Included bark is a structural defect in which bark is trapped between two branch unions and compressed, rather than forming strong, interlocking wood. Often mistaken for lightning damage after storms, included bark and weak branch unions can easily split under a heavy load.
When a Tree Crack Is Usually Not a Serious Concern
Cosmetic bark splits are superficial outer-layer defects, while tree structural defects compromise the internal wood, vascular system, and stability. Minor cracks typically look like:
Narrow bark splits
No movement in the trunk
Healthy canopy
Callus tissue forming around the wound
No signs of decay
If a tree trunk is cracked, it will compartmentalize the injury as a natural defense system, preventing damage, disease, and decay from spreading to healthy wood.
Is a Cracked Tree Trunk Dangerous? Know the Warning Signs
A tree trunk crack doesn’t automatically mean a tree is hazardous or needs removal, but when combined with structural defects and signs of decline, cracks can increase the risk of failure.
If you notice cracks in your tree trunk, look for these other signs that your tree may need extra attention:
Deep vertical cracks
Cracks extending through major limbs
Visible separation or movement, which requires immediate attention
Cavities or decay around the crack
Mushrooms growing near the trunk
Leaning after storms
Large dead branches
Peeling bark combined with cracking
Multiple trunk cracks
Should I Seal a Crack in My Tree?
A certified arborist should assess a cracked tree trunk before repair or treatment to reduce risk. When you notice a cracked tree trunk, take photos over time to monitor changes. Make sure to avoid:
Wound Paints & Sealants – Research has shown that wound dressings generally do not improve healing and may trap moisture or interfere with a tree’s natural defense processes.
Removing Loose Bark Unnecessarily – Removing loose bark exposes and increases the risk of damage to the living wood underneath the bark. Bark tracing should only be performed by an experienced certified arborist.
Reduce additional stress on a cracked tree by watering during dry periods, maintaining proper mulch, and protecting the root zone.
When to Call a Certified Arborist for a Cracked Tree
Massachusetts weather, from coastal nor'easters on Cape Cod to freeze-thaw cycles inland, can worsen existing trunk defects. Identifying these issues before winter can reduce the risk of storm-related failures.
A professional inspection by a certified arborist can determine whether a tree is safe. An arborist should evaluate trees with large or widening cracks, trunk movement, heavy limbs over infrastructure, signs of decay, recent storm damage, and multiple structural defects.
At Hartney Greymont, we have local arborists throughout Massachusetts located in Needham, Concord, Danvers, Cape Cod, and the surrounding areas who have the knowledge needed to diagnose and treat cracked trees.
Concerned about a cracked tree? Schedule a professional tree inspection with a Hartney Greymont certified arborist to evaluate its health and structural stability.
Tree Trunk Cracks: Frequently Asked Questions from Massachusetts Homeowners
No. Some bark cracks are superficial and heal naturally, while others affect the tree's structural stability. A professional inspection is the best way to determine severity.
Frost cracks develop when rapid temperature changes cause the wood inside the trunk to expand and contract faster than the bark, creating a vertical split.
Generally, no. Modern arboriculture does not recommend using wound paints or sealants because they rarely improve healing and may interfere with the tree's natural defense mechanisms.
It depends on the depth, location, and cause of the crack. Minor bark splits may compartmentalize over time, while severe structural cracks can compromise the tree's stability and create a route for decay to enter and progress.
Schedule an inspection if the crack is deep, continues to widen, is accompanied by decay or mushrooms, or if the tree is near a home, driveway, or other occupied area.
