Growing Summersweet

Otherwise Known as Clethra Alnifolia

Clethra alnifolia 'Ruby Spice' 1c
scottzona/Flickr/CC BY 2.0

Summersweet is a medium-sized deciduous shrub that adds color and fragrance to your garden with its late-summer blooms. The flowers are notable for their size and how late they bloom and their ability to bloom even in the shade. Summersweet is a versatile shrub that thrives in most climates and is suitable as a specimen plant or a hedge. It also attracts hummingbirds, bees, and butterflies.

Latin Name

The Latin name for summersweet is Clethra alnifolia. The plant belongs to one of only two genera in the Clethraceae (white alder) family, with Purdiaea being the other genus.

Common Names

For common names, you may see summersweet, sweet pepperbush, clethra, coastal sweet pepperbush, and poor man's soap.

Preferred USDA Hardiness Zones

You can plant summersweet in zones 3 through 9. It is originally from Eastern North America and grows naturally along the Atlantic coast and west to Texas. Its natural environment includes wet and swampy areas of woodland as well as marshes and river banks.

Size and Shape of Summersweet

This shrub usually grows to 3 to 6 feet in height but can be up to 8 feet tall. It typically spreads to 4 to 6 feet and forms an oval shape. Some varieties are shorter than average for the species.

Exposure

Plant this shrub in a site that receives full sun to part shade.

Foliage, Flowers, and Fruit

Summersweet's leaves are obovate and serrated, 1 1/2 to 4 inches long, and change from a glossy dark green in summer to yellow or brown in the fall. Make sure there are other plants around, as the plant will look bare until the leaves appear at the end of spring. The blooms are raceme flowers, 2 to 6 inches long, that may be white, pink, or rose-colored and have a sweet fragrance. After the bloom, the flowers leave small, dark brown seed capsule fruits that look like peppercorns. These may survive into winter in some climates.

Design Tips for Summersweet

Summersweet can tolerate salty air and even salt spray from nearby streets in urban areas. Its branches are dense, making it suitable for hedges or privacy screens (best in summer, of course). Being a water-loving plant, it works well at the edges of ponds, streams, and marshy areas. Elsewhere, summersweet looks nice when grouped in planting beds or lined up as a shrub border.

Look among these varieties of summersweet to find the best fit for your planting goals:

  • 'Creels Calico'
  • 'Crystalina'
  • 'Hummingbird'
  • 'Pink Spires'
  • 'Rosea'
  • 'Ruby Spice'
  • 'Sixteen Candles'

Growing Tips For Summersweet

This plant can work in a variety of soil pHs, types, and moisture levels. It prefers acidic, sandy soil that is moist but will tolerate clay soils and full shade. Water regularly as needed so the soil does not dry out. You can expand plant with seeds or use cuttings to make more shrubs. It also tends to sucker and will spread naturally if not pruned.

Maintenance/Pruning

You can deadhead to remove flowers past their prime, but otherwise, you can usually just leave this shrub alone unless you desire a neatly groomed look.

Pests and Diseases of Summersweet

The only common problem that this shrub faces are spider mites. Control can be as simple as spraying the leaves (front and back) to knock off the spider mites, though further intervention, such as predatory insects, and horticultural oils may be needed if mites are persistent.