University of Illinois Extension
Bruce Spangeberg

These articles are written to apply to the northeastern corner of Illinois. Problems and timing may not apply outside of this area.

Stateline Yard & Garden

Don't Neglect Pruning Shrubs

May 20, 1999

While often neglected, pruning is an important part of the maintenance of deciduous shrubs. Not only will pruning help control shrub size and attractiveness, it may also help keep shrubs flowering on a regular basis. Pruning deciduous shrubs is a fairly basic process with just a few basic guidelines to follow.

The first question often asked is when to prune? Late winter and spring are good times, with timing of flowering a consideration. For shrubs that have already bloomed, or are just starting now, flower buds formed last season. Prune soon after flowering. Those shrubs that bloom in mid to late summer flower on new wood produced this season thus are best pruned while dormant.

The second question is how to prune. There are two primary methods, renewal pruning and rejuvenation. Renewal pruning involves cutting out older stems near the base, which then promotes younger stems and new growth. Remaining stems may need some trimming back into a desirable shape. Some shrubs best pruned by the renewal method include lilacs, red twig and yellow twig dogwood, arrowwood viburnum, forsythia, kerria, deutzia, mockorange, and weigela. Most of these are best pruned right after they flower.

Rejuvenation pruning involves cutting all stems down to near ground level; leaving short stubs. This method is useful when a shrub has become overgrown with many stems massed together.

Among the shrubs that respond well to rejuvenation include Anthony Waterer spirea, honeysuckle, beautybush, indian currant, snowberry, and privet. Larger, older shrubs should not be rejuvenated in late spring or summer. Early spring is preferred for most.
After either method, new growth can be pruned back to help keep shrubs the size and shape desired. With hedges such as privet, prune them so that the lower portions are wider than the upper, so all leaves get equal light. This will help prevent the lower portions from dying out. Avoid pruning the side perpendicular to the ground or angling in toward the base. Hedges in poor shape should be rejuvenated and the new growth then pruned properly.

 

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