Clethra Species, Summersweet, Sweet Pepper Bush

Clethra alnifolia

Genus
Clethra (KLEE-thra)
Species
alnifolia (al-nee-FOH-lee-uh)
Synonym
Clethra alnifolia var. denudata
Clethra alnifolia var. glabella
Clethra alnifolia var. paniculata
Clethra alnifolia var. pubescens
Clethra alnifolia var. rosea
Sun Exposure
Sun to Partial Shade
Foliage
Deciduous
Height
6-8 ft. (1.8-2.4 m)
Spacing
4-6 ft. (1.2-1.8 m)
Hardiness
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)
Danger
N/A
Bloom Color
Pale Pink
White/Near White
Bloom Time
Late Spring/Early Summer
Mid Summer
Late Summer/Early Fall
Other Details
Category
Shrubs
Water Requirements
Average Water Needs; Water regularly; do not overwater
Foliage Color
Where to Grow
Bloom Characteristics
This plant is attractive to bees, butterflies and/or birds
Flowers are fragrant
Bloom Size
Other details
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
Non-patented
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
Regional

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

Rehoboth Beach, Delaware

Altamonte Springs, Florida

Orlando, Florida

Atlanta, Georgia

Winterville, Georgia

Glen Ellyn, Illinois

Terre Haute, Indiana

Iowa City, Iowa

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

Hilton Head Island, South Carolina

Summerville, South Carolina

Nashville, Tennessee

Aubrey, Texas

Bellingham, Washington

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Gardener's Notes:

5
positives
1
neutral
2
negatives
Sort By:
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C
ROSLINDALE, MA | April 2015 | positive

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 Sep...Read More

H
Watermill, NY | April 2015 | negative

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 t...Read More

R
Downingtown, PA | January 2014 | positive

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 Jerse...Read More

L
Mountain Top, PA | June 2013 | positive

I have had a fine experience with an older cultivar named 'rosea' here in zone 5. It stays within limits probably because it receives l...Read More

A
Fayetteville, NC | October 2012 | negative

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. Ne...Read More

S
Brockton, MA (Zone 6a) | August 2010 | positive

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

P
P
Summerville, SC (Zone 8a) | August 2006 | positive

We discovered this native plant growing at the woodline. It was a straggly plant but a few lovely racemes caught our attention, and my h...Read More

S
Oklahoma City, OK (Zone 7a) | May 2005 | neutral

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

Only reaches a heigh...Read More

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