An important maintenance practice that leads to a good flower display on shrubs is pruning. The key to success is to make certain it takes place at the right time of the year.
Spring flowering shrubs bloom on 1-year-old wood — stems that were new the season before. The flower buds develop from midsummer through fall for the following spring.
Summer flowering shrubs develop flower buds on the current season’s growth, and are known to “flower on new wood.” Pruning is done at different times and in different ways depending on which category your shrub falls into.
“Pruning can promote new plant growth, maintain plant size, encourage flowering, remove diseased or dead limbs and help control insect and disease problems,” says Sandra Mason, an extension educator in horticulture.
For spring flowering shrubs before June 15, she recommends pruning immediately after flowering.
“Pruning these shrubs in late summer, fall or early spring will remove the flower buds, and therefore, the flowers for the (next) season,” she says. “Spring flowering shrubs are generally pruned by the renewal method. Each spring, after flowering, prune out the largest stems of the shrub to the ground to stimulate new growth from the crown and remaining stems.”
It is suggested that no more than a third of the total stems be removed per year.
“Shrubs that bloom after June 15 can be pruned in early spring, generally February and March,” Mason further notes. “Many of these shrubs can be pruned by the scary rejuvenation method. Rejuvenation is the complete cutting of all stems down to 4 to 6 inch stubs. Rejuvenation is used when multi-stemmed plants become too large with too many stems to justify saving any 1- to 2-year-old growth. In other words, the shrub is a tangled mess of stems.”
But she says not to wait too long for this type of pruning.
“Especially large old shrubs should not be rejuvenated in late spring or summer,” she says.
Rejuvenation is done no more than every three to five years, should a shrub become unruly. Some summer flowering bushes, such as butterfly bush (Buddleia) are rejuvenated annually.
For help in determining when the best time of year to prune your shrub is, and by what method, contact the Master Gardener Helpline.
Email your home garden and lawn questions to email@example.com or call the Master Gardener Helpline at 630-955-1123. Visit our website at http://web.extension.illinois.edu/dkk/.
Julie Moore has been a master gardener volunteer with the University of Illinois Extension in DuPage County for 10 years and has a degree in ornamental horticulture from the University of Illinois.Tags: Gardening, Master Gardeners