Pruning Trees: Understanding Leaf Drop

 

One of the frustrating things about writing for the Internet is that advice given may be applicable for one area but wholly bad advice for another it is therefore incredibly important that the writer continually reminds themselves that they are writing for a global audience. This is incredibly important when discussing the the subject of pruning.

Even when pruning a tree of the exact same species of tree the local climate can have a profound effect upon when it should be done. Unfortunately many gardeners follow general pruning advice and find, to their great alarm, that they have inflicted near fatal damage to their trees. This can be even more upsetting if you have harmed a specimen tree that was expensive and difficult to replace.

The key to Successful Pruning

One of the most important factors in knowing when to prune, or more importantly - when not to, your trees. Understanding leaf drop and the reasons for it and other possible causes is key to knowing when it is best to set upon pruning of trees and shrubs in the garden.

A good knowledge of the various types of tree, especially those which you have used in your landscape garden, can make a huge difference to their growth rate and general wellbeing. There are two main classifications of trees, a tree can be deciduous or evergreen, deciduous trees drop their leaves in the autumn whereas evergreens keep them throughout the year.

Understanding Leaf Drop

If you live in a region which has a cold winter climate you will already be aware that many species of tree are not suitable for growing in your garden. In places where winter temperatures fall well below zero (say to -10c) during the winter months a great many evergreen trees will not survive. If you live in an area which has less harsh winters, where the winter temperatures are not likely to exceed -9c you will find that some evergreens, such as some acacia species, are able to withstand such weather. When we look at areas where the winter temperatures are likely to remain above freezing, at say around 5c, a great many more species of tree are able to grow and survive the winter.

When we plant trees in our garden which are not native to our location we are likely to notice differences in the behaviour of that tree when compared to how it grows in it's natural environment. This is especially so when we introduce trees into a cooler climate. Evergreens, excluding conifers, usually grow in warmer areas and when they are grown in a cooler area they can suffer from leaf drop. Evergreens will drop their leaves as a reaction to the cold (rather than for the genetic reasons of deciduous trees), even in the Mediterranean region some evergreens will suffer from leaf drop following a very cold night.

Pruning Trees

The pruning of trees is usually carried out when the tree is dormant. One of the most obvious signs that a tree is dormant is the lack of leaves. It is generally safe to prune a tree that has dropped it's leaves but this could not be further from the truth when it comes to evergreens which have suffered from leaf drop.

Pruning some types of tree in the winter can be disastrous leading to severe damage, stunting of growth and, ultimately death. During the winter such trees have a vastly reduced capacity to fight infection and they also heal far more slowly than in warmer months. This can lead to a severely increased risk of fungal or bacterial infection from which the tree would suffer greatly.

By understanding why your tree has lost it's leaves you will be able to avoid the terrible mistake of pruning trees at the wrong time of year.

 

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