Clethra alnifolia: Sweet Pepperbush

Close up of flowerLatin name: Clethra alnifolia
Common name: Sweet Pepperbush
Flowers: White, 2-6” spikes, blooms July - August10,12
Fruit or cones: Dark brown seed capsules with 1/8” diameter12
Height & Width: 3-8ft tall, 4-6ft wide10,12
Type: Deciduous shrub10,12
Habit: Shrub10,12
Wetland indicator category**: FAC, FACW17
Texture: Medium20
Growth rate: Medium19
Light: Full sun to part shade10,12
Moisture: Wet - moist10
Soil*: Ph< 6.8, sand and clay soils10
Zones: 3 to 912
Origin: Native to the lower 48 states10
Ecosystem benefits: Attracts bees, hummingbirds, and butterflies with flowers. Other mammals eat the fruit10,12.

Features: The flowers of this shrub an aesthetically pleasing and are beneficial because they attract hummingbirds, bees, and butterflies. The fruit of this shrub also provide food for some mammals. This shrub offers multiple seasons of interest with summer blooms, spring foliage, yellow fall color, and exfoliating bark in the winter10,12.

Siting: This shrub would do well in a raingarden or a spot in the yard that has a high content of sand and clay that stays moist12.

Care: Plant so root flare is visible at soil surface14. At planting, water the root ball daily with two gallons of water per inch of trunk diameter for two weeks, every other day for two months and then weekly until established. Modify water recommendations to reflect site drainage and rainfall. Apply 3” of mulch over the planted area. Do not allow mulch to touch the trunk14.

Pests: Plants are relatively pest resistant if cultural preferences are met10,12.

This plant does not appear on the following invasive plant lists on 3/2/2020:
USDA SC Invasive Plant Species
SC Exotic Plant Pest Council

Author: Cy Gettliffe

Image source:


  1. Armitage, A. (2001). Armitage’s manual of annuals, biennials, and half-hardy perennials. Portland, OR: Timber Press.
  2. Armitage, A. (2006). Armitage’s native plants for North American gardens. Portland, Oregon: Timber Press.
  3. Armitage, A. (2008). Herbaceous perennial plants: A treatise on their identification, culture, and garden attributes. Athens, GA: University of Georgia.
  4. Clemson Cooperative Extension Home and Garden Information Center.(2011). Flowers fact sheets. Retrieved from
  5. Clemson Cooperative Extension Home and Garden Information Center.(2011). Groundcovers & vines fact sheets. Retrieved from
  6. Clemson Cooperative Extension Home and Garden Information Center.(2011). Trees. Retrieved from
  7. Clemson Cooperative Extension Home and Garden Information Center.(2011). Shrubs. Retrieved from
  8. Dirr, M. A. (2009). Manual of woody landscape plants. Champaign, IL: Stipes Publishing.
  9. Gilman, E. F. (1997). Trees for urban and suburban landscapes. Albany, NY: Delmar Publishers.
  10. Lady Bird Johnson Wildflower Center University of Texas at Austin. (2012). Native plant information network. Retrieved from
  11. McMillan, P., Plant taxonomist Clemson University, personal communication.
  12. Missouri Botanical Garden Kemper Center for Home Gardening. Plant finder. Retrieved from
  13. North Carolina State University (2005). Plant fact sheets. Retrieved from
  14. Strother, E. V., Ham, D. L., Gilland, L. (2003) Urban tree species guide: Choosing the right tree for the right place.  Columbia, SC: South Carolina Forestry Commission.
  15. University of Florida, IFAS Extension. (2011). Southern trees fact sheet. Retrieved from
  16. USDA . Plant profile. (n/d).Retrieved from
  17. USDA. Plant wetland indicator status. (n/d). Retrieved from
  18. Vincent, E., Environmental horticulturist Clemson University, personal communication.
  19. Clemson Extension. Carolina Yards Plant Database. Retrieved from
  20. Gettliffe, C., Senior student of Horticulture, Clemson University, personal knowledge.

*Soil pH is determined using a professional soil test. Contact your Clemson University County Extension service for assistance Click on “local offices”.

**2012 Plant Wetland Indicator categories (quantitative derived)

Plant Wetland Indicator categories
Indicator Code Indicator Status Comment
OBL Obligate Wetland Almost always is a hydrophyte, rarely in uplands
FACW Facultative Wetland Usually is a hydrophyte but occasionally found in uplands
FAC Facultative Commonly occurs as either a hydrophyte or non-hydrophyte
FACU Facultative Upland Occasionally is a hydrophyte but usually occurs in uplands
UPL Obligate Upland Rarely is a hydrophyte, almost always in uplands