Carlcephalum viburnum is a deciduous shrub with ornamental qualities. The result of a hybrid cross, this plant has fragrant, snowball-like flowers in spring followed by red fruits and reddish fall foliage. Grow it in full sun exposures in a fertile, well-drained soil with organic matter for best performance.
Viburnum carlcephalum, normally seen in botanical literature as Viburnum x carlcephalum, is a member of the honeysuckle family, Caprifoliaceae. Common English names for this shrub include the carlcephalum viburnum or fragrant hybrid viburnum.
Selected in 1932, this hybrid plant originated in England at the Burkwood and Skipwith Nursery in Kingston-on-Thames. It is the result of a cross between Korean spicebush (Vibrunum carlesii) and Chinese snowball viburnum (Viburnum macrocephalum f. keteleeri).
Combining the fragrance or large flower cluster size of its parents, carlcephalum viburnum attains an upright, irregular but generally rounded shape from 8 to 15 feet high, slightly narrower in width. It is a deciduous shrub with leaves that are lightly fuzzy, oval-shaped and have a sheen on their medium to dark green color.
In April or May, branch tips bear pink flower buds that open white in snowball-like clusters, botanically called cymes, that are 4 to 6 inches in diameter. After pollination by insects, the flowers become tiny oval red berries that ripen to black by autumn. Foliage turns shades of orange-red, red and burgundy in mid-autumn before falling off the shrub.
It is regarded as hardy to USDA Hardiness Zones 5 though 7, although it is successful in cooler areas of Zone 8.
For more abundant flowering, position this shrub in full to partial sun exposures, where it receives at least four hours of direct sunlight. Soil should be fertile and well-draining, with organic matter incorporated. Soil pH can range from slightly acidic, neutral to slightly alkaline (6.0 to 7.8). A moist soil in the growing season sustains foliage and developing flowers and fruits; drought conditions retard growth, cause premature leaf drop, and often diminish flowering and fruiting displays.
Three popular cultivated varieties, or cultivars, exist for the carlcephalum viburnum. "Cayuga" dates to 1953 and is noted for its glossier leaves and slightly smaller mature size. Flowers and orange-red fall leaf color are similar to the species. "Chesapeake" has flowers with diminished fragrance and fruiting is also diminished. "Eskimo" has shiny dark green leaves that are flat and white flowers opening from ivory colored buds, lacking fragrance. Both "'Eskimo" and "Chesapeake" are the result of crossing "Cayuga" with service viburnum (Viburnum utile).