The Best Time to Prune Spring-Blooming Shrubs

Pruning Time Frame

• Schedule to conduct any pruning on spring flowering shrubs immediately after the flower display ends. Typically, this coincides with the emergence of new stem shoots and leaves. Do not delay pruning until much later in spring or early summer if possible. The longer time the new growth has to sprout and mature after the pruning wounds are made, the better. Unless a shrub's branch is dead or broken, do not conduct pruning of spring-flowering shrubs past late June. Prompt pruning maintenance is vital for late spring flowering shrubs, those that bloom right around Memorial Day to Flag Day, as must be pruned immediately after flowering wanes. The window for pruning is short.

Rejuvenation

• Sometimes, a spring-blooming shrub has become very large, untidy and lacking vigorous in growth and flowering. This often happens with yellow bells (Forsythia spp.), for example. While you may opt to wait to severely cut back the shrub to a height of 6 to 18 inches tall until after blossoming season ends, it's better to write-off the flowering for that year. Instead, prune back a shrub in very early spring. This lets the plant avoid expending energy on producing flowers, fruits or seeds. The early pruning leaves a long growing season for new buds to develop and sprout fresh, replacement shoots that become mature branches by late summer.

Caveat

• Do not prune spring-flowering shrubs past early summer. At this time of year, the new branch growth is maturing and beginning to form the initial tissues that become next spring's flower buds. By early fall, the flower buds are mature, but rest in a tightly closed dormant state. Unless there is an immediate safety concern about the shrub's branches blocking a view or being a tripping hazard, postpone pruning until next year. Otherwise you remove the tissues that bloom the next spring.

Recommendations

• While some spring-flowering shrub species are well-known -- azalea, viburnum, lilac, witchhazel, forsythia, almond bush, spirea -- and their prune time frame is straight forward, many rare or unusual species are available at plant nurseries. Talk to nursery staff about when to prune, or contact the county cooperative extension office and speak to a horticultural agent. Some spring-flowering shrub species may not respond well to pruning in general, or your area may be threatened by a disease or insect pest that attacks pruning wounds on shrubs. If you are uncertain, strike up a conversation with an experienced gardener or horticulturist. They love to talk about their plants, experiences and garden plots.