KC Gardens

Beware of the dead zone when pruning evergreens

The dead zone — areas without needles or leaves — is off-limits when pruning evergreens.
The dead zone — areas without needles or leaves — is off-limits when pruning evergreens.

Evergreen trees and shrubs are important features in our landscapes, but when it comes to pruning they are often misunderstood. Evergreens have specific needs and suffer when pruned poorly.

There are many factors to consider when pruning, including species, growth habit and function. Once you understand a few basic points, pruning becomes easy.

Don’t wade into the dead zone

The most important point to know about pruning evergreens is the dead zone, which refers to branch areas void of needles or leaves. To find the dead zone, start at the branch tip and work down until you reach the point where there are no needles or leaves. This is the start of the dead zone. At this point the branches are alive as they support the terminal growth with its structure and vascular system.

Why is the dead zone so important? Cutting off evergreen branches in the dead zone results in no new growth from the limb. In short, the branch will die. Never cut or prune into the dead zone.

Shearing is not pruning

Because people are confused about pruning evergreens they often shear to control plant size. Commercial landscapers do it because it’s quick and brainless. This sets a bad example.

Shearing is not pruning. Shearing is done on evergreens maintained as a formal hedge. Evergreens should never be sheared into balls, squares or rectangles: They look best when maintained in their natural state.

This means longer, arching limbs that reach out and look natural and graceful, adding interest to the landscape. When you punt the hedge shears, pruning is done using hand pruners, loppers or a hand saw.

Evergreen Boxwood
Don’t let evergreens such as boxwood get too overgrown. Adele Wilcoxen

Where to make the cut

Now that we know not to wade into the dead zone and to leave the hedge trimmers in the garage, it’s time to demystify where to make the cut.

Grab a branch or limb that you want removed and trace down the branch. Along the way you will find a number of side shoots, limbs or branches. If you run out of shoots with needles or leaves you have gone too far. This is the dead zone. Remember don’t cut past this point.

Make the pruning cut just to the outside of the desired branch. This branch will assume the growth of the tree or shrub. How far back an evergreen can be pruned depends on the amount of growth prior to reaching the dead zone.

Unfortunately, people are afraid to prune and wait until the plant is overgrown. At this point there is not much that can be done either by shearing or hand pruning. Take action before the plant gets out of hand.

Now you know the secret to evergreen pruning. As they say just do it. You can’t go wrong if you avoid the dead zone.

Dennis Patton is a horticulture agent with Kansas State University Research and Extension. Got a question for him or other university extension experts? Email them to garden.help@jocogov.org or visit KCGardens.KansasCity.com.