The snowball bush (Viburnum carlecephalum) is a popular variety of flowering shrub that thrives in hardiness zones 2 and above. Balls of sweet-scented, white blooms 5 inches across appear in early spring among 3-inch-long, silvery green leaves that will fade to purple as the season wears on. Growing to 10 feet tall, this specimen can quickly outgrow its boarders if not kept in check. Renewal pruning is the best way to keep your mature snowball bush looking great and blooming beautifully.
Prune old snowball bushes after flowering has ceased but before the fall. Viburnum species flower on old wood, or last year's growth. Pruning late in the season or in the spring will remove all buds, hence blooms, for that season.
Sterilize tools between each cut when working with suspected or confirmed cases of diseased wood. Good tool hygiene will prevent unnecessary spread of infection to otherwise healthy plant parts. Dip tools in a solution of 1/2 bleach, 1/2 water.
Prune the diseased, weak and oldest canes first on your very old snowball bush. Choose 1/3 of the oldest healthy canes and cut back to ground level.
Cut back the next 1/3 of the oldest canes to ground level in the following season after blooms have faded.
Make the final 1/3 cuts to remove the last of the old growth during the third season of pruning. This process encourages gradual emergence of new, healthy growth, a better overall shape, and more blooms in subsequent seasons.