University of Illinois Extension

Home Landscape Pruning

The word “pruning” actually means to cut in layers, and that is what we should all think about when pruning shrubs, said Richard Hentschel, U of I Extension horticulture specialist.

“We prune to make selective cuts, to maintain the natural form of a plant by preventing overgrowth, rubbing branches, and to direct future growth,” said Hentschel. “Over-grown plants become straggly, no longer accenting the landscape and our homes.

“Rather than just cutting the limb off to get it out of the way, cuts should be made to remove the branches without leaving a stub or disfiguring the plant.”

Pruning can either promote or restrict growth. Proper pruning can create a shrub with its greatest potential for flowering and a full canopy of foliage.

“Maintenance pruning is a yearly trimming to remove old, heavy wood and shaping the remaining new wood,” he noted. “A little pruning every year takes a lot less time than having to go in and try to recover a plant that has not been pruned in several growing seasons.

Photo of pruning“This kind of pruning is also called renewal pruning--you renew the plant over time, never losing the bulk or flower show.”

Good examples of this approach would be red twig dogwood and lilacs. By removing the older branches, you promote the bright red twigs on dogwood and better flowering on the lilac. Another good tip is to snip off the spent blooms on the lilac back to the first leaves below the flower for a better-looking plant the rest of the summer.

Rejuvenation pruning can bring back a troubled plant that is unmanageable using other kinds of pruning. Once rejuvenated, you can do renewal pruning to keep the shrub looking its best. This kind of pruning is most often done in late fall after the plant is dormant for the winter or in early spring before growth resumes. Most pruning books list the best way and time to prune.

To rejuvenate a suitable shrub, remove ALL growth, leaving about a 1-1/2 inch stem showing above the ground.

“Many home gardeners get confused as to the best time to prune for fear of pruning off flower buds, and, as a result, never prune at all,” Hentschel said. “Typically, if the plant blooms in the early spring, prune it soon after the bloom show is complete. That leaves the remaining season for the shrub to create blooms for next year.

Photo of pruning“If you prune too late in the year, you will be removing flower buds for the coming season. If you look at the buds on a viburnum or lilac in the fall, for example, you will see a big bud at the tip of the branch that is the flower for next year.”

For shrubs that bloom later in the spring or summer, pruning in early spring still leaves the possibility for a bloom show. Spireas are a good example of this type of shrub.

“There are always exceptions to the rule, and you should check the pruning book to be sure of the best time to prune,” he noted.

If there is a need to slow down a shrub’s growth, then a “summer pruning” may be in order. By removing some of the foliage that is supplying the food for the plant, next year’s growth should be less. Don’t get carried away as you can put your shrub into shock.

“Directional pruning is another term you will see and read about in pruning books,” he said. “This technique allows the person pruning to direct the new growth from the shrub. By pruning just above the bud or smaller side branch, the new growth will occur in the direction of that bud or side branch.”