“No, I don’t think you killed your beautyberry,” I replied to a visitor to the Extension Master GardenerSM office concerned that their pruning efforts had irreparably damaged a favorite shrub. One of a Master Gardener volunteer’s most interesting challenges is reassuring people that nature is very resilient! This is particularly true when it comes to pruning, which many home gardeners look upon with a sense of dread. I reassure them that the worst that can happen is severely diminished flower production for next season—but there are no overall adverse effects on long-term plant health!
As with most things involving gardening, there is an exception to this fact, which is to avoid pruning shrubs from mid-August until leaf fall. Late season pruning may encourage a flush of tender new growth that the onset of winter weather may kill back because it hasn’t had enough time to harden off.
Summer-flowering shrubs
Glossy Abelia (Abelia grandiflora), summersweet (Clethra alnifolia), crape myrtle (Lagerstroemia indica), rose of Sharon (Hibiscus syriacus), old-fashioned Weigela (Weigela florida), American beautyberry (Callicarpa americana), New Jersey tea (Ceanothus americanus), and Virginia sweetspire (Itea virginica) bloom on new wood. Botanically, these shrubs bloom on buds that develop on the growth that occurs in the spring of the current year. These species should be pruned in late winter or early spring (late March to early May) to promote vigorous growth early in the summer.
NOTE: We’ll discuss pruning hydrangeas in a future blog post. So, stay tuned!
What and when to prune
Does this mean you should put away your pruners now if you have summer-blooming shrubs? No, you can always remove damaged, dead, diseased, or double-crossed limbs (the “Four Ds”). You can also remove spent flower heads, but this is done for cosmetic purposes—remove only the flower head, not any other part of the plant!
Pruning techniques
When the time is right for pruning your summer-flowering shrubs, there are different approaches.
Rejuvenation is a drastic technique that works well on multi-stemmed, twiggy shrubs, and is typically done only every 3 to 5 years. It involves pruning all the stems back to about six inches above the ground.
Selective pruning involves removing specific branches and limbs to improve the overall appearance of the shrub, shape the plant for landscape use, and reduce the overall height of the plant. Do not remove more than one-third of a plant’s growth in any one year except when you do rejuvenation pruning on a set schedule.
Don’t shear! Reserve shearing with electric or manual hedge trimmers for broadleaf evergreens—it is not appropriate for deciduous shrubs!
Avoid “crape murder.” The drastic pruning of crape myrtles, commonly called “crape murder,” involves the wholesale reduction of the shrub’s height. This is equivalent to tree topping, which should not be undertaken under any circumstances! The result of such pruning is weakened structure and a reduction in vigor.
Article written by Bob Wardwell, Extension Master GardenerSM Volunteer.
More information
Pruning Trees & Shrubs: General Pruning Techniques
by Barbara Fair, Lucy Bradley, Anthony LeBude
Department of Horticultural Science, NC State University
Time to Maintain: Winter Pruning of Crape Myrtle Trees
by Beth Leonard, Extension Master GardenerSM Volunteer