Dealing with Frost Crack in Your Trees

Fluctuations in temperature allow frost crack to set in

Q: I planted a ‘Crimson King’ maple a few years ago and, at present, it is about 2½ m (8 ft.) high with a solid trunk. I have noticed a long split in the bark 15 cm (6 in.) above ground level and running 60 cm (2 ft.) up the tree. Is there a fix, or is this natural?

This is a disorder called frost crack, caused by a wide air temperature fluctuation between the inner wood and the outer wood during the dormant period. Cracks or splits usually appear on the south and west sides of the trunk, where the sun can warm up the bark.

Plants vary in susceptibility to frost crack. Deciduous trees are more prone than evergreens. Isolated trees are more prone than those grown in a woodland situation, and trees at their vigorous age show more cracking than very young or older trees. Trees grown in poorly drained sites are also more susceptible.

Once a crack has appeared there is not much you can do other than allow Mother Nature to take her course. If the crack is severe, you may want to consult with an arborist.

Continual cracking could allow wood-decaying organisms to enter. Help protect a susceptible tree from frost crack by wrapping its trunk with tree wrap in the fall or painting the trunk with a whitewash (white latex paint with an equal amount of water).

Originally published in BC Home & Garden magazine. For regular updates, subscribe to our free Home and Garden e-newsletters, or purchase a subscription to the magazine.