Summersweet Clethra (Clethra alnifolia)-Hort Answers - University of Illinois Extension
University of Illinois Extension

University of Illinois Extension

Hort Answers

Shrub

Summersweet Clethra
Clethra alnifolia

Summersweet Clethra form
Summersweet Clethra form
 
Features
Fragrant white flowers in small spikes, July and August; crisp, dark green foliage in summer; autumn color is yellow to a mild orange. 
 
Culture
Full sun to partial shade; prefers a moist to wet soil; tolerant of salt, compaction and some dryness; prefers slightly acid soil pH. 
 
Cultivars
  • 'Hokie Pink'- Pink flowers on a more compact plant
  • 'Hummingbird' - 2-3 feet tall, abundance of white flowers, yellow fall color\
  • 'Pink Spires' - 8 feet tall with pink flowers, dark green foliage and yellow fall color
  • 'Ruby Spice'- Rosy pink flowers, yellow fall color, 3-6 feet tall
  • 'Sixteen Candles'- White flowers, yellow fall color, 3-4 feet tall
 
 
Mature Height
4-8 Feet
 
Size
Small
Medium
 
 
Mature Width
4-10 Feet
 
Mature Form
Broad rounded to rounded, tends to sucker. 
 
Native To:
United States 
 
USDA Hardiness Zone
4 - 9 
 
Soil Conditions
Dry
Moist, Well-Drained
Wet
 
 
Tolerance
Dry Sites
Salt
Soil Compaction
Wet Sites
Wind
 
 
Exposure/Light Requirements
Full Sun
Partial Sun/Shade
 
 
Uses
Border
Massing
Specimen
 
 
Foliage Color
Green
 
 
Fall Foliage Color
Orange
Yellow
 
 
Pests and Problems

Environmental Damage


Additional pests and problems that may affect this plant:

Mites can be a problem in dry sites.
 
Additional Notes

 

 
Related Resources
Home, Yard & Garden Pest Guide
Illinois Commercial Landscape and Turfgrass Pest Management Handbook
U of IL - Distance Diagnosis through Digital Imaging
U of IL - Plant Clinic