Clethra is a group of flowering shrubs; some may even be more like small trees. There are both evergreen and deciduous varieties. These plants can be found growing in both temperate and tropical regions from Asia through Central and South America. They are found along woodland streams and moist forests in southern parts of the United States as well.
Most varieties of Clethra are also referred to as pepperbush because the mature fruit capsules are thought to resemble peppercorns. It has also been stated that their spicy-tasting seeds were once used for flavoring as a substitute for black pepper. Two of the more commonly known and widely used landscaping shrubs in this genus include Summersweet (C. alnifolia) and Cinnamon (C. acuminata) pepperbush. Both varieties make interesting additions to the landscape as specimen or group plantings. Some types may also be successfully grown in containers.
While they both exhibit clusters of white blooms in summer and green foliage that turns yellow to gold or orange in fall, there are still a couple of differences between these two Clethra shrubs. For instance, summersweet is normally grown as an ornamental shrub, whereas cinnamon pepperbush, which is larger, is usually pruned and grown more like a small tree. In addition, this particular variety is notable for its cinnamon-colored bark that eventually peels away to reveal a pink to reddish color beneath.
Both summersweet and cinnamon Clethra are great hummingbird attractors. They adapt easily to various growing conditions too. These shrubs usually prefer moist, slightly acidic soil in sun or partial shade. They also need plenty of growing room in the landscape. These shrubs will gradually spread by sending up new shoots, forming a dense thicket of shrubbery.
Once established, these plants require very little care. In fact, all they really need is deep watering during periods of drought. Although some species are quite adaptable, most Clethra shrubs resent overly dry conditions. Spring pruning may also be performed. Not only does annual pruning rejuvenate plants following winter but helps maintain their shape and overall size.
Other popular varieties include hummingbird summersweet, which is a dwarf form of C. alnifolia, and ruby spice summersweet, which has pink flowers rather than white ones. All Clethra species can be propagated through seeds, cuttings, and division. Seeds can be sown in spring or fall while cuttings may be rooted in summer. The suckers can be dug up, divided, and transplanted in spring or fall, depending on the climate.