Frost Cracking: The real story behind “Exploding Trees”

You may have seen dramatic headlines recently about “exploding trees.”

While attention‑grabbing, the term is misleading. What people are referring to is frost cracking, also called southwest injury.

Southwest injury occurs on sunny winter days when the southwest side of a tree trunk warms up, then cools rapidly when the sun goes behind a cloud or sets. The bark and wood contract at different rates, causing stress that can lead to a vertical crack.  This is sometimes accompanied by a loud snap.

Thin‑barked species such as maples, redbuds, and apples are most susceptible. Trees already stressed by drought, herbicide injury, insects, or disease are also at higher risk.

If you want to prevent this from occurring the future, then consider these helpful tips.  Install white tree guards or tree wrap in late fall.  These white tree guards may help prevent the crack from occurring by reflecting the sun and preventing overheating on the bottom of the trunk.  The wrap should be moved in early spring.  

Keeping trees well-watered before winter may help.  Specialists out of University of Minnesota say that dry conditions going into the winter can make plant tissues more susceptible to cold damage.

Avoid mechanical injuries to the trunk.  Existing injuries are usually the starting point for where these cracks originate.

Healthy trees often recover over time, but stressed trees may carry the damage for life. The bottom line is that frost cracking is real.  It is manageable and it is far lass dramatic than the term “exploding trees” suggests.

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