If you have ever heard what sounds like gunfire go off in the dead of winter and it isn't hunting season, it could be the sound of tree bark cracking. Frost crack is not a drug, but an occurrence distinct in thin barked trees, deciduous trees and trees that stand isolated rather than in groups or stands.

This isn't to say other types of trees don't develop frost crack. Trees that grow quickly and vigorously are more apt to develop frost cracks than very young or old trees. One can also find trees with frost crack that have some sort of weakness in the bark, which occurred to the tree earlier.

When and why does frost crack occur? Typically in late winter or early spring due to water building up within the tree's inner bark or xylem. As the wood expands and contracts with significantly fluctuating temperatures and the bark does not contract at the same rate as the inner phloem, cracking occurs.

Trees that are growing in poorly drained sites are more subject to frost cracking than are those growing in drier, better drained soils.  Trees suddenly left exposed by felling are highly susceptible as well.

Frost cracks can be up to several feet long. You may not notice the cracks until spring and they are typically on the southwest side of the tree. Some cracks heals n the summer and then reopen again in the winter. If cracking and healing reoccurs the tree can develop frost ribs.


The wood beneath the frost crack is rarely damaged but the cracks can serve as sites of entry for wood decay organisms, including insects, fungi and bacteria. Timber damaged in this way is unsuitable for use in buildings, etc.


The sloughing or peeling of the bark is a normal process, especially in the spring when the tree begins to grow. The outer layers of the bark are dead tissue and therefore they cannot grow, the outer bark splitting in order for the tree to grow in circumference, increasing its diameter. The inner bark cambium and phloem tissues are living, and form a new protective layer of cells as the outer bark pulls apart. Most tree species try to seal the edges of wounds by forming a callus layer. The wound’s edges begin to form this callus during the first growing season after that crack appears and the callus layer will continue to grow and after many years, the wound may close over entirely.


Normal furrowed bark has a layer of bark over the wood below, however bark may peel or fall off the tree in sheets (river birch), plates (sycamore and pine), strips (cedar) or blocks (dogwood).

To reduce frost crack, avoid using fertilizers late in the growing season. Also, protect your trees from physical damage that can occur from lawn mowers, trimmers car bumpers, grazing animals, spades, etc. You can protect young trees in winter with paper tree wrap. Wrap your tree from ground level to the first main branches.

Trees most susceptible to frost cracking are: apple, crabapple, beech, cherry, golden-rain tree, horsechestnut, London planetree, some maples, pin Oak, tulip Tree, walnut, and willow. With the proper knowledge of what frost crack is and a few preventative measures, it is possible to try and protect your trees throughout the winter.