On average, viburnum shrubs need relatively little pruning. However, it never hurts to practice occasional viburnum pruning each year to maintain shape and overall beauty.
When to Prune Viburnum
While light pruning can be performed anytime throughout the year, it’s best to leave any major shearing or severe pruning for late winter or early spring.
Of course, much of viburnum pruning depends on the variety grown too. In many cases, pruning just after flowering but before the setting of seedpods is sufficient. If frost is imminent in your area, you should put off pruning so as not to damage new shoots.
How Much Can a Viburnum Shrub be Trimmed Back?
Typically, viburnum shrubs should be trimmed back about a third of their size each year. Most pruning is done for shaping purposes only. However, old or overgrown shrubs may require some rejuvenation. Thinning out of unsightly branches can help open these shrubs up as well.
How to Prune Viburnum
Pruning viburnums is not always necessary but when it is, you want to do it properly. Young shrubs can be pinched to help maintain shape, choosing the most attractive, upright stem and pinching side shoots as needed for appearance. Then you can begin maintaining your shrub annually by cutting it back just above the nodes so the plant can continue to put out new shoots. Oftentimes, taking up to a third of the shrub can achieve natural-looking results without harming the viburnum.
For overgrown shrubs, reshaping may take several years of pruning to correct. Cut these plants close to the ground, leaving sturdier stems in place and removing any thin ones.