Viburnums have long been one of the most popular flowering landscape shrubs, with more than 150 species available, including deciduous, evergreen, and semi-evergreens shrubs. With an almost infinite number of cultivars available, you can find a one to suit any garden—wet or dry, sun or shade, natural or formal, shrub or tree, native or exotic. For most viburnum shrubs, bloom times span from early spring through June, followed by attractive fruit and outstanding fall foliage.
Fast-growing viburnums are well-behaved members of the honeysuckle family. They can be grown as either shrubs or trees, although tree forms may require some pruning to achieve the desired shape. The U.S. National Arboretum has done extensive breeding to create many hardy, pest-resistant varieties.
There is no single type of viburnum foliage. It can be rounded, lance-shaped or toothed, smooth, velvety, or rough. There are some evergreen viburnum varieties, in addition to many deciduous varieties with outstanding fall color. Viburnums work well as hedges, or in mass groupings, and also make interesting specimen plants or anchors in borders.
Most viburnums have either white or pinkish flowers which are sometimes fragrant. The fragrant varieties are native to Asia. The flowers themselves come in three major types: flat clusters of florets, flat umbels outlined with larger flowers resembling lace-cap hydrangeas, and dome-shaped, snowball-like clusters.
Almost all viburnums produce attractive clusters of fruit that are popular with birds, wildlife, and humans. However, most viburnums are not self-pollinating and will require another variety to cross-pollinate in order to yield fruit. Viburnum can grow to be 20 feet tall!
|Botanical Name||Viburnum spp.|
|Common Name||Viburnum, American cranberry bush, hobblebush|
|Plant Type||Deciduous shrub|
|Mature Size||3 to 20 feet tall, depending on cultivar|
|Sun Exposure||Full sun to partial shade|
|Soil Type||Rich, moist, well-drained soil|
|Soil pH||5.5 to 6.6, but also tolerates slightly alkaline soil|
|Boom Time||Early to late spring, depending on species|
|Flower Color||White, pinkish|
|Hardiness Zone||2 to 9 (USDA), depending on species|
|Native Area||Temperate regions of Northern Hemisphere|
|Toxicity||Non-toxic to humans and animals
In general, viburnums are not terribly particular about where they grow, though they prefer fairly rich, moist soil. Viburnums do not transplant well once established, so the best strategy is to plant well-established container-grown plants and take care to choose a location where the shrub will have room to grow. Early spring is the best time for transplanting, giving them a full season to adjust.
After planting, add a 2-inch layer of mulch to keep the soil moist and hold in moisture. During hot weather, the shrubs should be watered every 7 to 10 days. Little pruning is necessary, though some species can be trained to form tree-like plants by removing competing stems.
Viburnums prefer full sun but will tolerate part shade.
These shrubs prefer fairly moist, well-drained soil, but they do not like to have their roots soaking in water. Viburnums like a slightly acidic soil but many types will tolerate alkaline soil.
A deep watering every week is usually sufficient, either through rainfall or irrigation. Native varieties that are well established have a moderately good tolerance for drought.
Temperature and Humidity
Viburnums prefer moderate conditions, though the preferences vary greatly depending on species. Extremely hot weather requires extra watering, and very cold temperatures can stunt the plant or cause dieback.
Most viburnums need little more than one application each year of a balanced, time-release fertilizer mixed into the soil in spring. Once well-established, most shrubs do well without any feeding.
Varieties of Viburnum
- 'Nannyberry' (Viburnum lentago): This species grows in USDA hardiness zones 2 to 8 to a mature height of about 12 feet with a 10-foot spread. It prefers moist shade but will weather sun and dry soil. Lace-cap type flowers in creamy white appear in mid- to late-May
- 'Swamp-haw viburnum' (Viburnum nudum): This plant grows in zones 5 to 9, where it achieves a mature height of about 12 feet with a 6-foot spread. It prefers a location with full sun to partial shade. This variety produces white flowers in late June, followed by clusters of round drupes
- 'Hobblebush' (Viburnum lantanoides): Formerly known as Viburnum alnifolium, this variety grows in USDA hardiness zone 4 to 7. It achieves a maximum height of about 8 feet with a spread of 12 feet. A native to northeastern to mid-Atlantic North America, it tends to grow a bit disorderly and is probably best suited for a naturalized setting. Flat umbels of white flowers appear in May, followed by red fruit clusters that age to the typical blue-black. The leaves are large and fuzzy, and this is one of the earliest viburnums to develop fall colors of reddish-gold.
Leggy shoots can be trimmed back in early summer to maintain the shrub's form. Broken, dead, or diseased branches should be removed as soon as you notice them.
You can propagate from softwood cuttings during the summer or simply layer branches in the fall. By spring there should be a new plant you can cut off and move.
How to Grow Viburnum From Seed
Growing viburnum from seed can be done, but it's a laborious process. Most experts suggesting propagating from cuttings instead.
Potting and Repotting Viburnum
Plant virburnum in large containers with drainage holes; they need well-draining soil and full sun. To keep away soggy soil, add 10%-20% perlite to the mix.
Viburnum are hardy, but might drop leaves in colder weather. Prune off dead leaves and branches. Come spring, your shrub will recover.
The fact that few pests bother viburnums is one of the reasons they have become so popular in the landscape. In 1947 the viburnum leaf beetle (VLB) arrived in Canada, and made its way to New York state in 1996. The VLB, Pyrrhalta viburni (Paykull), is capable of great damage and is being closely watched. The best way to combat viburnum leaf beetles is to remove egg-infested leaves and to encourage predatory insects. Some organic pesticides are also effective, but avoid synthetic pesticides, which also kill beneficial insects.