How to Prune a Viburnum Bush
Viburnum is a large genus of flowering shrubs belonging to the honeysuckle family of plants. Viburnums bloom in a range of hues and are grown as specimen plants, foundation plantings and en masse as hedging. Viburnum flowers in the spring and early summer with the formation of small round purple-black berries following bloom. Always prune viburnum in the late spring or early summer immediately after flowering to prevent you from removing the buds for next year's bloom which form as early as the late summer of each year.
Maintenance prune your viburnum throughout the growing season as needed to remove spent blooms, broken branches and dying foliage. Inspect the shrub each time you water with secateurs in hand. Catching any problems early and removing them will prevent disease from taking hold and spreading. Harvest blooms if desired for use in cut flower arrangements. Place all cuts at least 1/4 inch above a leaf node to maintain and encourage branching.
Hard prune your viburnum for shape and size in the late spring or early summer once a year or less frequently as needed. Remove up to one third of the shrub's foliage in a single pruning session but no more in order to limit stress on the shrub. Selectively prune weak branches in the interior of the shrub to encourage fresh growth and rejuvenate spindly growth. Thin the interior if needed to allow sunlight and fresh air circulation or remove crossing branches. Set the desired height and spread parameters by shearing off the tips of the branches as needed.
Water your viburnum after any pruning session to lessen the stress on the plant and give the roots a boost to issue new growth. Mulch around the base of the shrub with an organic material such as compost, shredded bark or cocoa bean hulls to hold moisture in and keep weeds away. Replenish the mulch each year as it breaks down into the soil.