Snowball viburnum (Viburnum opulus 'Roseum') bears puffy white flower clusters during spring months. The bush's leaves have three prongs and are somewhat similar to maple leaves, but they do not change color in fall months. Snowball viburnum can reach 12 feet in height and in width. Native to Europe, this cultivar of viburnum has been grown throughout the United States since the Colonial era, according to University of Arkansas Extension. Snowball viburnum is a hardy landscape shrub that performs best in full sun and should be pruned annually for a neat appearance.
Wait until the blossoms have fallen from your snowball viburnum, sometime in late spring or early summer. While you can prune this viburnum in late winter once frost danger has passed, doing so will reduce the snowball blooms, according to University of Rhode Island Extension horticulturalists.
Check over the snowball viburnum for dead, diseased or damaged branches. Dead branches should have little, if any, foliage or flowers, and damaged or diseased branches will bear wounds or discoloration.
Clip off dead, diseased or damaged branches at their base. In between each cut, spray your pruning tools with the disinfectant spray to avoid spreading bacteria. Disinfect your tools again when you've removed all dead and diseased wood. Throw the wood in a garbage bin rather than a compost.
Cut back the branches on your viburnum if you feel it's grown too tall or leggy. Determine how far back you want to trim the plant, then cut the stems back. Use hedge clippers to cut more growth at one time and make even cuts to give the viburnum a neat appearance.
Thin out old growth from the canopy of your snowball viburnum. This increases air circulation inside the canopy, which promotes plant health, says University of Rhode Island Extension. Identify older, woody stems and branches that compress other branches. Then cut these off at the base or at a Y-intersection using hand pruners.
Remove any broken or weak branches you encounter in the canopy or at the exterior. Trim off any branches that grow vertically to encourage outward and upward branching.