Clethra alnifolia

Common Names

Summersweet, Sweet Pepperbush, Coastal Sweet Pepperbush, White Alder, Alderleaf Clethra, Alderleaf Pepperbush, Summersweet Clethra, Clethra

Summary

Clethra alnifolia is a native eastern North American deciduous shrub that typically grows 3–8 ft tall and 4–6 ft wide, often forming colonies by suckering, it features glossy dark green leaves with serrated margins that turn golden yellow in autumn and fragrant bottlebrush-like flower spikes in midsummer, usually white (pink in some cultivars), attracting bees, butterflies, and hummingbirds, mature plants may bear brown seed capsules that persist into winter, and the plant tolerates coastal salt spray, making it suitable for wetlands, swamps, streamsides, and moist woodland edges, in cultivation Clethra alnifolia prefers moist, acidic soils but tolerates a wide range of conditions, including full sun to partial shade, and is hardy in USDA zones 4–9, it can tolerate coastal salt spray, the shrub spreads slowly by suckers, making it useful as a hedge, border, or naturalized planting, and flowering occurs on new growth, so pruning in late winter or early spring helps control size while preserving blooms, it is generally pest- and disease-free, with occasional spider mites in hot, dry locations, propagation can be by cuttings or seed, and numerous cultivars exist, including Hummingbird, Pink Spires, Ruby Spice, Sixteen Candles, Anne Bidwell, and Vanilla Spice

Lifecycle

Perennial

Height

3-8 feet

Spread

48-72 inches

Hardiness Zones

Zones 3-9

Sunlight Requirements

Ideally partial sun to partial shade, tolerates full sun to full shade

Soil Type

Moist, acidic, well-drained soil.

Soil Drainage

Moist, well-drained, acidic soil

Soil pH

Acidic soil, ideal pH below 6.0 (roughly 4.5–5.5)

Bloom Color

White, with pink or light pink in some cultivars

Bloom Time

Summer

Foliage Color

Dark green foliage that turns yellow in autumn

Fall Foliage Color

Golden yellow to golden brown

Leaf Lifecycle

Deciduous

Growth Rate

Slow-growing

Seasons of Interest

Summer and Fall

Propagation Methods

Seeds, Cuttings, Division

Attracts Wildlife

Bees, Butterflies, Hummingbirds, Birds