Growing a snowball bush is doable with the right attention to detail and research. The decorative flowering bush known as a "Snowball Bush" is most often one of two separate species. One is a type of viburnum known as Viburnum opulus, while the other is a species of hydrangea with the Latin name Hydrangea paniculata grandiflora. The hydrangea is also known as a "pee gee hydrangea" as well as a "snowball bush." Both types of snowball bush produce large, spherical clusters of white flowers in spring. Both are also hardy bushes that require little care once they are established, making them easy and enjoyable to grow.
The snowball bush, whether a viburnum or a hydrangea-type, grows best in USDA Hardiness Zones 5 through 7. The viburnum variety can also be planted in Zone 4, although the bushes should be protected with burlap wrapping during Zone 4's harsher winters. The hydrangea variety of snowball bush does not do well in Zone 4, although they are more likely than the viburnum variety to thrive in Zone 8.
Snowball bushes need several hours of sun per day in order to thrive. The hydrangea variety blooms best in up to five hours of daily sun. When choosing a place to plant a snowball bush, consider the risks of the bush being shaded out by buildings or larger trees or bushes. When in doubt, choose an area that may get too much sun over an area that may get too little. A snowball bush will suffer if it is placed in heavy shade. Snowball bushes that are being shaded out may be transplanted in the fall, after the bush has lost all its leaves.
In addition to choosing a sunny area, choose an area with moist, well-drained soil in which to plant a snowball bush. In heavy clay or other poorly-drained soils, improve drainage by working sand or ground tree bark into the soil at least six inches deep. Do not plant the bush too deep in the ground. Most snowball bushes do best when planted at the same depth in which they were planted at the nursery. Plant snowball bushes in early summer or fall to allow the plant to establish itself well before winter comes.
Once the bush is planted, water it thoroughly, and continue to water the bush at least once per week during dry weather. Since neither the viburnum nor the hydrangea variety of snowball bush tolerates transplanting well, do not expect it to bloom during the first season after it's planted. Avoid trimming or pruning the bush during the first year after it is planted, except if necessary to remove dead or diseased foliage.
Both types of snowball bush are 12 to 20 feet in both height and width when fully grown, although they can be trimmed yearly to maintain a size as small as two to three feet. However, an extensive pruning sometimes prevents the bush from blooming the next spring. Older snowball bushes often have their main trunk die out and instead begin to put up new shoots directly from the ground. If this occurs, remove the main trunk carefully from among the new shoots.