The snowball bush (Viburnum opulus) produces large global flower clusters that are pure white. The clusters commonly measure 1/2 inch across and appear in May. On many cultivars the flowers are sterile. In varieties that are not sterile red tiny berries will be produced that persist into the winter for added color interest. The shrub will normally attain heights of 10 feet with a spread of 10 feet. The foliage is three lobed and looks similar to sugar maple tree leaves.
Plant in full sun to partial shade for best results. The plant is exceptionally hardy and can easily withstand transplant if moving is required at a later date. Group in a mass planting for a screen or hedge, or plant singular as a decorative specimen. The bush is extremely cold hardy and can withstand temperatures that drop to minus 30 degrees Fahrenheit.
The snowball bush is extremely adaptive to various soil conditions. According to the University of Connecticut, the pH does not matter to the well-being of the shrub. It is advisable to add humus when planting to help the soil retain moisture without being waterlogged. Add peat moss at a ratio of 50 percent peat moss with 50 percent garden soil.
Remove all dead branches in early spring. The snowball bush does not require drastic pruning. Simply prune to keep the bush shape pleasing and to allow air flow.
The snowball bush's new growth shoots are susceptible to aphid infestations. If the aphids are allowed to flourish on the shrub the leaves and stems will appear distorted and unsightly. Wash aphids away every three to four days by using a garden hose and a soft cloth. Pesticides for aphids can also be applied. Follows the directions on the label for application instructions.
Viburnum borers will cause dieback on snowball bushes. If the infestation is allowed to persist the plant may even die, according to the University of Wisconsin. If the plant begins to show signs of sickness look closely at stems for cracks, swellings or emergence holes. Any stems that sustain damage should be promptly pruned from the shrub to prevent borer infestation. Borers commonly infect the shrubs through wounds or because the plant is not healthy. Pesticides containing permethrin can be applied in June and reapplied in July to help control heavy infestations. Follow the directions on the pesticide label for application.