is important when pruning flowering shrubs. It can make the
difference between a delightful show and a disappointment.
Summer bloomers such as spirea and butterfly bush form buds on the
current year's new growth. They should be pruned in late autumn or
early spring before the new flower buds form.
of spring bloomers form on "old wood," which means they form during the
late summer and autumn of the previous year. Therefor, the best time to
prune spring bloomers is right after
you enjoy the floral display, before the flower buds form on the new
summer growth. If you prune them at any other time of year, such as
early spring or fall, you sacrifice future blooms.
Annabelle hydrangea (Hydrangea
and PeeGee (H. paniculata) also bloom on the current year's growth but
rarely need significant pruning.
The Endless Summer hydrangea flowers on
both old and new wood. Old flowers should be pruned out sparingly to
maximize new blooms.
Late summer or fall bloomers such as
Rose-of-Sharon (Hibiscus syriacus) are best pruned in early summer.
Pruning in late summer or early fall encourages new
leafy growth that will not mature in time to harden before the first
frost, which usually damages the tender new growth on shrubs pruned too
late in the year.
Source: University of Illinois Extension; Nancy
Pollard, horticulture educator, 708-679-6889.
Timber Press Encyclopedia of Flowering Shrubs
and Garden Center