Clethra, Summersweet, Sweet Pepper Bush 'Hummingbird'

Clethra alnifolia

Family: Clethraceae
Genus: Clethra (KLEE-thra) (Info)
Species: alnifolia (al-nee-FOH-lee-uh) (Info)
Cultivar: Hummingbird



Water Requirements:

Requires consistently moist soil; do not let dry out between waterings

Sun Exposure:

Full Sun

Sun to Partial Shade

Light Shade




Foliage Color:

Unknown - Tell us


36-48 in. (90-120 cm)


36-48 in. (90-120 cm)


USDA Zone 3b: to -37.2 C (-35 F)

USDA Zone 4a: to -34.4 C (-30 F)

USDA Zone 4b: to -31.6 C (-25 F)

USDA Zone 5a: to -28.8 C (-20 F)

USDA Zone 5b: to -26.1 C (-15 F)

USDA Zone 6a: to -23.3 C (-10 F)

USDA Zone 6b: to -20.5 C (-5 F)

USDA Zone 7a: to -17.7 C (0 F)

USDA Zone 7b: to -14.9 C (5 F)

USDA Zone 8a: to -12.2 C (10 F)

USDA Zone 8b: to -9.4 C (15 F)

USDA Zone 9a: to -6.6 C (20 F)

USDA Zone 9b: to -3.8 C (25 F)

Where to Grow:

Unknown - Tell us



Bloom Color:

White/Near White

Bloom Characteristics:

This plant is attractive to bees, butterflies and/or birds

Flowers are fragrant

Bloom Size:

Unknown - Tell us

Bloom Time:

Mid Summer

Late Summer/Early Fall

Other details:

Unknown - Tell us

Soil pH requirements:

5.6 to 6.0 (acidic)

6.1 to 6.5 (mildly acidic)

Patent Information:

Unknown - Tell us

Propagation Methods:

From softwood cuttings

By tip layering

Seed Collecting:

Unknown - Tell us


This plant is said to grow outdoors in the following regions:

Lula, Georgia

Iowa City, Iowa

Northfield, Massachusetts

Redford, Michigan

Baldwinsville, New York

Davidson, North Carolina

Star, North Carolina

Cincinnati, Ohio

Dublin, Ohio

Mogadore, Ohio

Norristown, Pennsylvania

West Chester, Pennsylvania

Old Hickory, Tennessee

Rockwood, Tennessee

Linden, Virginia

South Boston, Virginia

Vancouver, Washington

Ellsworth, Wisconsin

show all

Gardeners' Notes:


On Jul 19, 2015, Rickwebb from Downingtown, PA wrote:

This dwarf form of Summersweet was registered as a new cultivar in 1991. It grows about 3 feet high and is at least 4 feet wide, but in time is widens more. It will sucker a lot in really moist or draining wet soils. It has often been replaced by a newer cultivar of 'Sixteen Candles' because the former has some drooping twigs and flower clusters while the latter holds its flower clusters and end twigs more erect.


On Mar 14, 2009, cedar18 from Lula, GA (Zone 7b) wrote:

I may regret putting this shrub in a perennial border since it suckers, but it has a nice form and I was sold on it after watching a hummingbird visit it. This plant did not do well for me in partial shade (poor soil, granted) but it has thrived in sun, adequate water and good soil.


On Aug 6, 2006, winging from Cincinnati, OH (Zone 6a) wrote:

Thrives in partial shade but as noted above, it can be late to leaf out. My mature plant is a bit sprawled, so I've supported it with a ring support. This improves the overall appearance of the plant. I otherwise pretty much leave this alone, except for random deadheading of the old bracts in the spring and summer by snapping them off when I happen to be near-by. White flowers lighten up shady areas.


On May 21, 2005, sanity101 from Dublin, OH (Zone 5b) wrote:

It's very late to leaf out in the spring. Every year we think it's dead, but around mid-May it finally sends its leaves out and looks fine. That coupled with a somewhat leggy structure makes it more of a 'backyard' plant than something for the front walk, but it smells so wonderful, and holds its flowers for a long time. Does attract bees though. (plants referenced are in part-shade)


On Apr 9, 2003, kategw wrote:

Wonderful fragrance, longlasting flowers, good yellow fall foliage, neat winter structure with seed pods lasting all winter.