Viburnums are a large group of deciduous and evergreen shrubs. There are over 150 species of viburnums, according to Marjan Kluepfel, a master horticulturist with Clemson University, and each species has its own cultivars. Viburnum flowers grow in bunches on the ends of the branches and are usually white or pink. Many viburnums also feature fall berries. Viburnums range widely in size, from rather short to over 25 feet tall. Basic viburnum care is the same regardless of the species.
Species of viburnum that are native to the United States usually grow well in USDA hardiness zones 2 through 9. Those species that are native to Asia, including the popular Viburnum awabuki Chindo, are limited to warmer climates (hardy to zone 5). Check the species of viburnum before you purchase it and choose one that is best for your particular climate.
Different viburnum species have different light requirements, but in general, the more sun exposure, the better the plant will bloom. The intense, hot rays of the afternoon sun will scorch the leaves, so place your viburnum in an area that receives morning sunlight and filtered or dappled afternoon shade if you live in a hot climate.
Soil and Water
Viburnums thrive in soil that is rich in organic matter and slightly acidic. Amend hard soil with 5 inches of pine straw or 2 to 3 inches of bark. This will help the soil drain better, which is important in the prevention of root rot. Keep the soil relatively moist but not waterlogged. While established plants don't need a lot of watering, you should lightly water when there is less than 1 inch of rain per week and deeply water during periods of drought.
Check your shrub often for signs of fungal diseases or insect pests. Spots on the leaves are indicative of a fungal infection and can often be avoided by watering from below. The fungi will not hurt your plant, but it is unsightly. Aphids, spider mites and scale are also known to bother viburnums. If you see these tiny bugs on your plant, treat the viburnum with a general insecticide.
Prune in the spring, before the leaves uncurl or buds open. Remove old, weak or dead branches (called canes). Thin out overly bushy plants, especially if you are training the viburnum as a tree. If you want to shape the plant, wait until the flowers have bloomed so you don't shear off any of the unopened buds.