Proper Pruning for Picture-Perfect Plants

By Ron Dieter, Sunnyfield Greenhouse & Gardens

March 10, 1998

Pruning landscape shrubs correctly is easy to do but seldom done. Some homeowners are reluctant to do any cutting for fear of making a mistake and damaging the shrub. Accumulated old wood, broken branches, and neglected growth make the shrub more of a liability than an asset to the landscape. Other gardeners lose all control when they get clippers and saws in their hands, leaving a trail of butchered barberries and wounded weigelas in their wake.

The common lilac, Syringa vulgaris, is one shrub that is usually pruned incorrectly or not at all. When the shrub finally gets too large and forlorn, the homeowner reaches for the chain saw and whacks it back to waist high. Now it's uglier than ever and insects and diseases will try to finish the plant off for good. Proper pruning on an annual schedule will make for an attractive plant and help control bugs and diseases (including mildew, a common ailment of lilacs). Now is a good time for pruning because the lilacs are bare and the framework can be easily inspected.

Examine the shrub and cut off any old woody stems at the ground. This allows sunlight into the plant, stimulating new growth from the crown. Now breezes will move more easily through the plant, deterring mildew. Removing old decayed wood makes the silhouette more attractive during the winter months. Remember that lilacs and other spring flowering shrubs bloom on one-year wood so don't do a lot of pruning on the remaining younger branches until immediately after blooming.

Bridalwreath Spirea is another plant that is often pruned incorrectly. Some books say that bridalwreath makes a nice formal hedge, but I have never seen one that looked good. Never shear bridalwreath or shape it geometrically. Doing so results in an ugly plant with green tufts on top of bare stemmy twigs. Allow it to grow naturally, forming slender arching branches covered with white flowers in spring. You can prune away old dead wood and broken branches now. If your bridalwreath is old and overgrown, renew it by cutting the whole shrub off at the ground. It will quickly regrow in a couple years, becoming a graceful Victorian shrub. The bridalwreaths in front of the Kewanee Library were renewed in this manner several years ago.

Take a few minutes to educate yourself on the correct way to cut away limbs and branches and properly shape trees and shrubs. Floyd Giles of the University of Illinois has written the best booklet I have ever read on grooming woody landscape plants. It is entitled Pruning and Care of Trees and Shrubs, Circular U-5040.

The first section of the booklet describes the three different methods of pruning and when to use each method. Drawings illustrating shrubs before and after pruning make it easy to grasp the concepts. The sections that follow discuss maintaining hedges, multi-stem trees, vines, and large shade trees.

The most valuable part of the booklet for me is the last section, "How To Prune Common Shrubs." Each shrub is listed in alphabetical order with a short paragraph explaining when to prune and which method to use. More than a hundred different shrubs are listed and discussed. This booklet is like an operator's manual for your landscape and a valuable resource. It is available for $3.50 from the Henry-Stark Cooperative Extension Unit on the Black Hawk East Campus.