Summersweet clethra, Clethra alnifolia, also known as coastal sweet pepperbush, grows naturally along streams in the eastern United States from Maine to Florida. This upright deciduous shrub has fragrant white flowers arranged in showy 3- to 5-inch racemes. It blooms in July and august, providing beauty to the late summer garden as well as food for bees and butterflies. The fruit, though not showy, is eaten by birds.

Clethra is a good plant for shady wet sites where it can grow to 8 feet tall and 6 feet wide. It forms a multi-stemmed shrub or even a colony. In partial shade or full sun it has dense, glossy green foliage that can turn yellow in mid-October. It likes acid soil and tolerates salt spray, but is not a plant for dry sites. Spider mites and dieback can be a problem in dry sites. When planted in the proper site it is insect and disease resistant.

‘Sixteen Candles’ is the top seller, though ‘Hummingbird’ is the best know cultivar. They are compact shrubs with white flowers. ‘Rosea,’ ‘Pink Spires’ and ‘Ruby Spice’ are three pink-flowered cultivars. ‘Ruby Spice’ is the darkest pink. This pink color holds even in the coastal plains. ‘Sherry Sue’ is a relatively new introduction, sporting white flowers and bright red stems. Look for most of these cultivars in the collections of the JC Raulston Arboretum (JCRA). Additionally, ‘September Beauty,’ noteworthy for flowering later in the season, can be found in the JCRA mixed border.

Another interesting species, Clethra tomentosa, showing pubescent foliage and very long racemes, also graces the Arboretum collections. Currently missing from the Arboretum collections, but worthy of inclusion in the landscape, is Japanese pepperbush, Clethra barbinervis, exhibiting beautiful cinnamon-colored exfoliating bark as it matures. Use clethra for summer flowers in wet, shady areas, particularly where the fragrance can be appreciated. Learn more at jcra.ncsu.edu.

David Goforth