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Coastal Sweetpepperbush (Clethra alnifolia L.)

Also known as sweet pepperbush.

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Range - Expand

Native or Not Present

This tentative map is based on our own research. It may have limited data on Canada and/or Mexico, and there is some subjectivity in our assignment of plants as introduced vs. expanded. Read more in this blog post.


Found on moist, often poorly-drained sites with acidic, often sandy soils. Natural habitats include swamps, bogs, and forests, especially flatwoods of the southeastern coastal plain. Prefers swamps with more stagnant water, adjacent to ponds or lakes rather than those along rivers or streams. Usually occupies later-successional stages of habitats in which it occurs, and can be found in the understory of old-growth forests. Occasionally found in roadside ditches, but usually less abundant in anthropogenic habitats.

This species tends to be more abundant and dominant in and near Virginia's coastal plain; in this region it can be found in a wider range of habitats, including drier sites such as upland forests. Farther from this region, it becomes progressively more scattered and uncommon, and more limited to wetlands.

This species has a stronger preference for acidic soils than specifics of moisture. Although it can grow on more neutral soils, it does not take advantage of greater nutrient availability and is not competitive with other vegetation. Tolerates sandy or clay soils, but is more demanding of consistent moisture in these soil types. Typically requires significant organic matter in the soil.


Clethra alnifolia is frequently used in landscaping, where it is valued for its attractive and fragrant flowers and foliage which attract bees and butterflies, and its ability to bloom well in shade. It tolerates a wide range of lighting conditions from full sun to fairly heavy shade, waterlogged soils and clay soils, and soil erosion. It requires consistent moisture, however, and is unsuitable for dry sites, especially when planted in sun. Its use is also limited by its late leafing out, a characteristic some people find undesireable.

It can be grown and pruned as a hedge, and also can be planted in rain gardens and along margins of constructed wetlands. It can also be grown successfully somewhat inland from its native range; its absence in the wild reflects lack of competitiveness with other vegetation rather than inability to survive.

In its range and when on suitable (moist, acidic) soils, this shrub can be planted, and is often effective, for slowing the establishment of trees or other taller woody plants in areas where taller vegetation is undesireable and would create the need for costly pruning, such as along edges of paths or roads, under power lines, or near pipelines. Such planting can save significantly on maintenance costs.

Coastal Sweetpepperbush | Fire Effects Information System (FEIS) (About This Site)

Clethra alnifolia (coastal sweetpepperbush) | USDA PLANTS Database (About This Site)

Clethra alnifolia | Go Botany (About This Site)

Clethra alnifolia (Sweet Pepperbush) | Missouri Botanical Garden Plant Finder (About This Site)

Summersweet Clethra | Virginia Tech Dendrology Factsheets (About This Site)

Clethra alnifolia | CABI Invasive Species Compendium (About This Site)

Clethra alnifolia | Biota of North America Project (BONAP) (About This Site)

Clethra alnifolia | NatureServe Explorer (About This Site)

Clethra alnifolia | Flora of North America (About This Site)

Coastal Sweet Pepperbush | Maryland Biodiversity Project (About This Site)