When to Prune Shrubs in Colorado

Colorado's seasons play a pivotal role in pruning times.

The main goal of pruning is to promote new growth on your shrubs. In Colorado, pruning time depends on whether the shrub flowers in the spring or summer.

Spring-Flowering Shrubs

Prune after blooming, since the buds of flowers develop during the summer and fall. Pruning during fall or before bloom can result in fewer blooms. Examples include forsythia, honeysuckle and lilac. Dead-head (remove of spent blooms) during the summer to conserve the shrub's energy and promote the development of more seed pods.

Summer-Flowering Shrubs

The buds for these shrubs develop early in the growing season, around mid-spring. In Colorado, prune these in early spring (early to mid-March) before blooming begins. Examples include Rose of Sharon and most butterflybush.

Thinning

Thinning requires removing one-third of the oldest wood. Cut this wood to the ground, which in turn promotes new, better-flowering growth from the ground.

Shearing and Shaping

Shearing is quick but will result in a woody, unattractive plant over time. This method cuts back wood with new buds or growth, although it gives a rounded or desired shape for a short time.

References

• Colorado State University Extension: Pruning Flowering Shrubs
• Colorado State University Extension Master Gardener Program: Pruning Flowering Shrubs