Urban Arborists

Seasonal Activities

What do we do in winter? This is the question that many of our clients ask. Most trees and shrubs are dormant, though evergreens will still carry on photosynthesis whenever the temperature is high enough. In dormancy, one supposes, the plants are mainly turned off, so why work?

As it turns out, the dormant season is the best time to perform many of our routine pruning tasks. Everything is not indeed turned off, but processes are slowed and next year’s growth is safely stored away in buds. Most important, the pests and diseases that feed on growing plants are at their least active. Certain trees that are subject to devastating diseases – American elms, for example – should only be pruned in dormancy. Other trees and shrubs can also be pruned in dormancy with less concern for potential exposure to pests and diseases. The only exception to this rule are those that are subject to fungal canker diseases. A number of canker diseases are active in autumn, even after leaves fall, so such plants should be left until midwinter to prune.

There is another advantage to dormant pruning, particularly for deciduous trees and shrubs. At this time of year, we can clearly see the structure of each plant and each stem. It is – often to our clients’ surprise – easier to identify weak, diseased and dead branches. It is also easier to envision a tree’s best future shape and so to direct it by structural pruning.

In pruning trees, it is almost always better to prune smaller amounts more frequently, rather than large amounts at long intervals. The pruning wounds are smaller, and it costs the tree less energy to close them. Thus, there is less opportunity for pests and pathogens to become established. Also, smaller doses of pruning allow the arborist to fine tune the tree’s structure, both for beauty and for health.

Give us a call. We will answer with alacrity! We ARE at work this winter.