How To Prune A Flowering Shrub
The most important thing to know about pruning a flowering shrub is that it might not need it.
Unless a flowering shrub is severely overgrown, you should probably leave it alone. Flowering shrubs have a naturally loose, lovely shape that shouldn't be messed with—other than to remove dead or damaged wood. Besides, if pruned incorrectly, most flowering shrubs won't bloom, or will bloom in an odd, uneven fashion.
However, if the shrub is severely overgrown, you can prune it to encourage better growth and flowering. Good candidates would include lilacs, honeysuckle, mock orange, forsythia, witch hazel, and other large, rampant growers that have gotten out of control.
With all of these, if you choose, you can simply cut them back to several inches, a process known as "stumping." They will send out fresh new growth in spring.
A less radical approach is to selectively thin out about one-third of the branches from the base of the shrub, cutting them off at the base of the plant with a loppers or small pruning saw as needed. The following year, cut out another third and the following year, another third until you have nothing left but fresh, younger growth.
As a rule, prune a flowering shrub as soon as possible after it's flowered (but also at the start of temperate weather) so it has plenty of time to produce flowers for next year. That means:
- Prune spring-flowering shrubs in late spring or early summer.
- Prune summer-flowering shrubs in late winter or very early spring since a fall pruning would stimulate tender new growth, which would get zapped by winter cold.
- Prune shrubs with late-summer or fall flowers or berries in late winter or very early spring for the same reason.
