Take steps early to weather-proof trees

Getting caught with your plants down is embarrassing — but it can also be dangerous.

Recent snowstorms wreaked havoc with many gardens — broken branches, bent trees, sagging limbs and damaged structures.

Why have there been so many problems? Blame the weather for not encouraging the leaves to fall.

Leaf drop is an active growth process. Healthy trees from most species form an abscission layer of hardened cells between the twig and the leaves as temperatures cool gradually and consistently. This blocks the flow of nutrients and water to the leaves, and they stop manufacturing chlorophyll.

Once the plant no longer manufactures chlorophyll, the natural orange, red, yellow and purple pigments are no longer masked, and they start to show through. The brittle abscission layer then breaks off in the wind.

The problem this season is that the temperatures remained very warm until late in the year. Many species of trees never formed an abscission layer, and the leaves were happily growing in summerlike temperatures when the snowstorms came.

The problem was aggravated for some varieties by an earlier frost. Once leaves freeze, the abscission layer does not form and dead leaves hang on the branches, making them susceptible to breakage.

If the storm left you picking up branches, propping up limbs and tying up twigs, you are not alone. Like all good gardeners, the real trick is to learn how to prevent problems in the future.

Although it might be small consolation now, the real prevention is to plant trees that aren't prone to such problems. Some trees — like honey locust or black locust — have small leaves that aren't going to catch much snow. Other trees — including ginkgo, most ash varieties and lindens — drop leaves early in the season.

Trees that drop their leaves late — or never at all — include English oaks, sycamores and the flowering pears. The breakage is intensified on the pears because their branches usually extend from the same point on the trunk and the wood is often brittle.

Other trees with weak angles and brittle wood include the Siberian elm, the silver maple, cottonwoods, poplars and willows. These trees are among the most likely to go down after an early winter snowstorm.

Another factor is improper pruning. One common — but destructive pruning practice — is topping, where trees are pruned indiscriminately at a given height without regard to their growth responses. Topping destroys the strength and integrity of trees and opens them up to decay and insect problems.