These attractive shrubs are grown for the small, five-lobed, sweet-scented white or pink flowers that cluster at branch tips in mid- to late summer. Tolerate many soils but do best in moist, organic, slightly acid, well-drained soil. Prefer partial shade but can adapt successfully to less light as well as to full sun, though they need some shade where summers are very hot. Remove some old wood from base annually before spring growth begins. Not browsed by deer.
C. acuminata. CINNAMON CLETHRA. Zones US, MS; USDA 6-7. Native to mountain areas of Virginia, Georgia, and Alabama. Grows to 812 ft. (rarely 20 ft.) tall and wide. Habit is open, even gaunt, so that polished-looking bark in various shades of cinnamon, tan, and reddish brown is displayed beautifully. Fragrant white flowers in 3- to 6-in. spires. Oblong, 3- to 6-in.-long leaves are dark green in summer, then turn golden yellow in autumn.
C. alnifolia. SUMMERSWEET, SWEET PEPPERBUSH. Zones US, MS, LS, CS; USDA 6-9. Eastern U.S. native to 410 ft. tall and wide, spreading slowly by suckers. Thin, strong branches form a vertical pattern. Tooth-edged, dark green, 3- to 4-in. leaves appear late in spring, turn golden yellow in fall. At bloom time, each branch tip carries several 4- to 6-in.-long spires of tiny, gleaming white flowers with a spicy perfume.
Selections include the following; most grow about as wide as tall.
'Anne Bidwell'. To 46 ft., with extra-large flower clusters late in the season.
'Crystalina'. White-flowered, dwarf form to 2-212 ft. tall.
'Creel's Calico'. To 4 ft.; foliage irregularly variegated in cream.
'Hummingbird'. Reaches 212312 ft. tall and spreads by suckers to form large colonies.
'Pink Spires'. To 4 ft., with deep pink blooms.
'Ruby Spice'. To 68 ft.; dark rosy pink blooms. Wonderful for borders, shade plantings. Spreads by suckers to make a broad clump. Tolerates coastal conditions.
'September Beauty'. Late bloomer; reaches 46 ft.
'Sixteen Candles'. Similar to 'Hummingbird', but flower spikes are held upright like candles on a birthday cake.
'White Dove'. Compact, profusely blooming dwarf reaching 23 ft.
C. barbinervis. JAPANESE CLETHRA. Zones US, MS, LS; USDA 6-8. Slow-growing plant reaches 1518 ft. tall and about one-half to two-thirds as wide; has attractive, peeling, glossy gray-to-brown bark when mature. Produces drooping, 4- to 6-in. clusters of fragrant, bell-shaped white flowers. Oval, pointed, sharply toothed, dark green leaves turn bright yellow in fall. 'Variegata' has leaves attractively splashed with golden yellow.