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Summersweet clethra

Flowers of summersweet clethra.

A wide variety of butterflies and songbirds are attracted to summersweet clethra for its nectar and seeds.  Native to the eastern United States, it has lustrous green leaves in the spring, spiky white or pink fragrant flowers during the summer, golden yellow leaves in the fall, and interesting, delicate dried seed capsules in winter to provide exceptional four-season interest.  

This plant has some cultivated varieties. Go to list of cultivars.


Botanical name:

Clethra alnifolia

All common names:

Summersweet clethra, Summersweet, Clethra, Sweet Pepperbush

Family (English):


Family (Botanic):


Tree or Plant Type:

  • Shrub

Native Locale:

  • North America

Landscape Uses:

  • Foundation,
  • Hedge,
  • Massing,
  • Mixed border,
  • Specimen

Size Range:

  • Medium shrub (5-8 feet),
  • Small shrub (3-5 feet)

Light Exposure:

  • Full sun (6 hrs direct light daily),
  • Partial sun/shade (4-6 hrs light daily),
  • Full shade (4 hrs or less of light daily)

Hardiness Zones:

  • Zone 4,
  • Zone 5 (Chicago),
  • Zone 6,
  • Zone 7,
  • Zone 8,
  • Zone 9

Soil Preference:

  • Acid soil,
  • Moist, well-drained soil,
  • Wet soil


  • Wet sites,
  • Occasional flooding,
  • Alkaline soil,
  • Road salt

Seasons of Interest:

  • early winter,
  • midwinter,
  • midsummer,
  • late summer,
  • early fall,
  • mid fall,
  • late fall

Flower Color & Fragrance:

  • Fragrant,
  • Pink,
  • White

Shape or Form:

  • Oval,
  • Round,
  • Thicket-forming,
  • Upright

Growth Rate:

  • Slow,
  • Moderate

More Information:

Summersweet clethra (Clethra alnifolia)
Summersweet clethra (Clethra alnifolia)
photo: John Hagstrom
Tree & Plant Care

Oval to rounded form reaching 6 to 8 feet high and 4 to 6 feet wide
Cultivars vary in size and color.
Best in moist to wet soils, tolerant of soil pH, part shade to full sun.
Slow to leaf out in spring.
Spreads by suckering roots forming wide colonies.
Flowers on new wood, prune to control size in spring.
Tolerant of aerial salt spray.

Disease, pests and problems

No serious problems

Native geographic location and habitat

Native to the eastern coast of the United States.

Attracts birds & butterflies

Songbirds, including robin, goldfinch, and warblers are attracted to the seed capsules.
Nectar source for swallowtail butterflies and hummingbirds.

Bark color and texture 

Bark is brown;  multi-stemmed.

Leaf or needle arrangement, size, shape, and texture

Simple, alternate leaves;  2 to 4 inches long, sharply serrated, medium to dark  green above, paler beneath, turns a golden-yellow in fall.

Flower arrangement, shape, and size

Fragrant, five-petaled flowers in upright spikes on end of branches. Color varies by cultivar from white to pink.

Fruit, cone, nut, and seed descriptions

Interesting, delicate, dried seed capsules persist through winter.

Cultivars and their differences 

  Hummingbird  (Clethra alnifolia 'Hummingbird'):  2  to 3 feet high and wide; rounded form; white flowers; flower clusters are larger and open earlier than the species.

Ruby Spice  (Clethra alnifolia ‘Ruby Spice’):  4  to 6 feet high and wide; oval to rounded form; rosy pink flowers.

Sixteen Candles (Clethra alnifolia 'Sixteen Candles'):  2 to 3 feet high and wide; rounded form; white flowers.

Vanilla Spice  (Clethra alnifolia 'Caleb')4 to 6 feet high and 3 to 5 feet wide; upright to rounded form; white flowers are larger than those of the species.

Location of Clethra alnifolia (Summersweet clethra) at the Arboretum