Viburnum and Physocarpus
by SCMG Steven Hightower
P. o. 'Coppertina’ in the garden
Shrubs are part of the foundation and backbone of any garden. In addition to structure and permanence, they can contribute interesting foliage, seasonal flowers, fruit or berries, and, in many cases, fall color. Two shrubs that form part of the foundation of Kate Roach's garden, featured this month, are Viburnum and Physocarpus.
Viburnums are a versatile and useful group of plants of over 150 evergreen, semi-evergreen and deciduous species. They combine handsome foliage, lovely flowers, often-interesting berries and ease of care. Flowers are normally snowball-shaped or lace-cap, creamy white to pink-flushed. Leaves are glossy, often leathery and berries can be dark red to blue to black. Native mostly to Northern temperate zones, some also hail from South Africa and Southeast Asia.
Viburnums grow generally to about 4-6 foot in height, although some, such as V. sieboldii, can become small trees. Depending on species, they are generally hardy in USDA zones 3-9, and take sun or shade. Not drought tolerant in Sonoma, they need supplemental water in summer. Most prefer moderately fertile and well-drained soil.
In Kate Roach’s garden she grows Viburnum rhytidophyllum (Leatherleaf viburnum), Viburnum macrocephalum (Chinese snowball viburnum), Viburnum carlesii (Korean spicebush) and Viburnum x burkwoodii (Burkwood viburnum).
Viburnum rhytidophyllum (Leatherleaf viburnum) is one of the hardiest of the genus, with dark green, leathery, wrinkled leaves with deeply etched veins.
In the spring, lace-cap clusters of small ¼-inch flowers appear at the ends of thebranches. These abundant flat-topped flower clusters may be from 5 to 8 inches across and creamy yellow in color, and are mildly fragrant. In the fall, the plant sports oval-shaped red berries. V. rhytidophyllum will tolerate shade, but blooms best with a fair amount of sun. It prefers well-drained soil that’s a bit acidic, but will tolerate heavier soil.
Viburnum macrocephalum (Chinese snowball viburnum) is evergreen or
semi-evergreen with clusters of large snowball-shaped flowers in spring—lime green initially, turning to pure white. It likes sun to partial shade, well-drained soil and grows eventually to 12 ft plus.
Viburnum carlesii (Korean spicebush) is deciduous and grows to 4 to 6 feet highand wide. Snowball-like clusters of waxy flowers emerge pink, and then gradually fade to white. This viburnum is noted for a heady, intoxicating fragrance (hence the common name). In late summer to fall, the red berries turn to black. V. Carlesii is tolerant of adverse conditions and generally trouble-free.
Viburnum x burkwoodii (Burkwood viburnum) is a hybrid between V. carlesii and Viburnum utile. It's semi-evergreen here in Sonoma, maturing at about 6-8' tall by 6' across. Red or pink buds open to white flowers tinged with pink in
mid-spring. Clusters of berries change from green to red to black by early autumn. Fall color varies from brilliant red to dull burgundy. Burkwood viburnum likes full sun to partial shade and prefers moist, well-drained, slightly acidic soils, but it is quite adaptable to poor soils.
Viburnum x burkwoodii
Physocarpus, commonly called ninebark, is a deciduous multi-stemmed shrub to 5' to 10' tall with equal width, generally grown for striking foliage in brown, maroon, or lime, depending on the variety. Ninebark is named for the exfoliating bark on its mature branches, which peels in strips to reveal several layers of reddish to light brown inner bark. The bark provides winter interest but during the growing season is often hidden by the foliage. Pinkish white flower clusters in early summer show off against the dense colored leaves and burgundy stems. Physocarpus can be used as a specimen, or massed in shrub borders, or as hedge or screen. It is generally not particular about soil and can grow happily with low or moderate water in full sun to part shade.
Kate Roach says, “I have several of the Physocarpus opulifolius ‘Coppertina’, which have copper new leaves that turn red in the fall with beautiful white spring flowers. Another cultivar, ‘Summer Wine’, has darker foliage--more purple--with the same flowers and fall color. They are striking specimens alone or in a shrub border, where I have most of mine.”
Website Editor Sara Malone says, ‘Coppertina’ is my favorite. I also grow ‘Diablo’, which is dark brown - some I cut down, others I let get big. They are more or less part of a hedgerow of shrubs, providing good contrast to greens. My third Physocarpus is ‘Darts Gold', which is lime-gold in color-- I'm a sucker for colored foliage. I don’t like the flowers much, as I feel that they interfere with the statement that the foliage makes, but they don’t last long and the small fruit clusters that follow are an even more intense coppery red than the leaves!
Physocarpus opulifolius ‘Coppertina’
Physocarpus opulifolius ‘Summer Wine’. This hybrid of Physocarpus ‘Nana’ and Physocarpus ‘Diablo’ features darkly colored crimson-red foliage. It matures at about 5'–6' high x 6' wide.
Physocarpus opulifolius ‘diablo’
Physocarpus opulifolius ‘Diablo’ is a large deciduous shrub--to 8-10 ft--with purple/bronze foliage. This species is native to Missouri.
Physocarpus opulifolius 'Darts Gold' is a compact, mounded, deciduous shrub
that usually matures to about 5’ tall and as wide. In spring the emerging leaves are an eye-catching, golden-yellow hue. Later in summer, the foliage ages to a quieter lime-green, and in autumn, its greenery shifts back to yellow with an overlay of bronzy-red.
Physocarpus opulifolius Darts gold