Clethra Species, Summersweet, Sweet Pepper Bush

Clethra alnifolia

Family: Clethraceae
Genus: Clethra (KLEE-thra) (Info)
Species: alnifolia (al-nee-FOH-lee-uh) (Info)
Synonym:Clethra alnifolia var. denudata
Synonym:Clethra alnifolia var. glabella
Synonym:Clethra alnifolia var. paniculata
Synonym:Clethra alnifolia var. pubescens
Synonym:Clethra alnifolia var. rosea
View this plant in a garden



Water Requirements:

Average Water Needs; Water regularly; do not overwater

Sun Exposure:

Sun to Partial Shade



Foliage Color:

Unknown - Tell us


6-8 ft. (1.8-2.4 m)


4-6 ft. (1.2-1.8 m)


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:

Pale Pink

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:

Late Spring/Early Summer

Mid Summer

Late Summer/Early Fall

Other details:

Unknown - Tell us

Soil pH requirements:

5.1 to 5.5 (strongly acidic)

5.6 to 6.0 (acidic)

6.1 to 6.5 (mildly acidic)

6.6 to 7.5 (neutral)

Patent Information:


Propagation Methods:

From softwood cuttings

From seed; direct sow outdoors in fall

From seed; winter sow in vented containers, coldframe or unheated greenhouse

By simple layering

By serpentine layering

Seed Collecting:

Allow seedheads to dry on plants; remove and collect seeds

Properly cleaned, seed can be successfully stored


This plant has been said to grow in the following regions:

Rehoboth Beach, Delaware

Altamonte Springs, Florida

Orlando, Florida

Atlanta, Georgia

Winterville, Georgia

Glen Ellyn, Illinois

Terre Haute, Indiana

Brockton, Massachusetts

Wayland, Massachusetts

Blissfield, Michigan

Manchester, New Hampshire

Frenchtown, New Jersey

Baldwinsville, New York

Brooklyn, New York

Carmel, New York

Croton On Hudson, New York

Chapel Hill, North Carolina

Fayetteville, North Carolina

Leicester, North Carolina

Parkton, North Carolina

Fredericktown, Ohio

Columbia, Pennsylvania

Downingtown, Pennsylvania

Mountain Top, Pennsylvania

Conway, South Carolina

Summerville, South Carolina

Nashville, Tennessee

Aubrey, Texas

Bellingham, Washington

show all

Gardeners' Notes:


On Apr 5, 2015, coriaceous from ROSLINDALE, MA wrote:

Blooms for about a month beginning in July here, though there's some genetic variation in bloom time, and some forms don't bloom till September. The sweet fragrance is lovely, and floats on the air.

Very shade tolerant, but flowering is best in full sun.

This species does spread by suckering, but I have not found it to spread quickly in ordinary well-drained garden soil. In the wild, this is a wet-soil plant.

Blooms on new wood, so this can be pruned as needed in the spring. Grows quickly.


On Apr 4, 2015, hamptons from Watermill, NY wrote:

This is a thug if it is planted in good soil. Like trumpet vine, it takes a few years before it gets established and starts taking over the area. Pulled it out three years ago and still find runners. Stay away.


On Jan 3, 2014, Rickwebb from Downingtown, PA wrote:

One of my favorite shrubs! I have seen it in its native habitat in the draining wet, acid, sandy soils of Delaware and southern New Jersey where it does sucker alot. In average well-drained soils of most landscapes it does not go crazy suckering. It only does it some, and it is easy to propagate from thise few suckers. It has fragrant flowers in July and August loved by pollinators. It has good yellow fall color. It is a clean plant, not twiggy messy as many popular deciduous shrubs as honeysuckle, weigela, or deutzia.


On Jun 13, 2013, laineygirl from Mountain Top, PA wrote:

I have had a fine experience with an older cultivar named 'rosea' here in zone 5. It stays within limits probably because it receives less than half a day's worth of sun, and maybe because of our more northern climate.


On Oct 20, 2012, AnitaEdge from Fayetteville, NC wrote:

This shrub is beautiful when it is blooming, and it keeps a compact form if pruned every fall after blooming. But it is very invasive. New plants are coming up all around the shrub, under my house and throughout my yard. I pull them up, but they keep coming back. They are coming from the root system of this shrub. The sooner I get rid of this shrub, and all of its roots, the better I'll feel.


On Aug 5, 2010, Sarahskeeper from Brockton, MA (Zone 6a) wrote:

This plant will catch your nose before you see it if you're in low lying woods. Heavenly.


On Aug 24, 2006, patp from Summerville, SC (Zone 8a) wrote:

We discovered this native plant growing at the woodline. It was a straggly plant but a few lovely racemes caught our attention, and my husband eventually moved it to a backyard flowerbed where it has rewarded us with lush growth and many gorgeous, fragrant mid-July flowers. It's 5' tall and has spreads by underground runners. Bees, butterflies, and hummingbirds visit the flowers; fruits are eaten by birds and small mammals. It thrives in wet, acidic soil. I had confused this plant with Itea virginica, but the experts at DG's ID forum convinced me otherwise based on the bloom time.


On May 25, 2005, smiln32 from Oklahoma City, OK (Zone 7a) wrote:

Moderate growth. Flower spikes are white and last a long time. Attractive to butterflies and bees.

Only reaches a height of 5'. Does well in partial shade. Likes moisture.