Clethra (Clethra alnifolia), commonly called "summersweet" because of its heavy fragrance, grows native in woodlands along the eastern coastline from Maine to Florida and into parts of Texas. The intense summer heat has very little effect on the plant, and it produces an abundance of flowers during the mid-summer heat. Flowers are either white or pink. They appear on long 6-inch racemes. Flowers attract a wide range of butterflies, bees and hummingbirds. Dried seed capsules follow the flowering and are adored by birds.
Clethra enjoy partially shady to full shade conditions. They will grow in full sunlight but require constantly moist soil during the height of summer. The shrub grows up to 8 feet in height with a 6 foot spread. The shrub growth appears oval in shape. Several cultivars are available for gardens that require a more compact size to fit small areas.
The shrub enjoys acid soil conditions with ample organic matter. It grows well in areas of persistently damp soil and is often found beside bodies of water. The plant enjoys having its roots wet. Clethra cannot tolerate extended drought conditions. The shrub grows well along the coastline in areas of high salt where other shrubs will die.
Foliage appears dark green. The leaves are oval shaped and measure up to 4 inches long and 2 inches in length. The leaves begin to appear late in the spring.
The fall color of the clethra is a brilliant yellow and gradually turns brown. The colors can be maintained on the shrub for several weeks before the leaves begin to fall from the shrub.
Propagation normally occurs from seeds easily. The suckers of the shrub are dug up and transplanted to new areas of the garden. Root cuttings can also be taken from the plants stems and started in a rooting mixture.
The clethra is disease-free. The only pests that plague the shrub are spider mites during the height of summer. Watch for fine webbing, foliage that turns dry and tiny red dots. If spider mites are detected, hose the plant off thoroughly using water every few days until the spider mites are completely controlled.