Korean Rhododendron (Rhododendron mucronulatum)-Hort Answers - University of Illinois Extension
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University of Illinois Extension

Hort Answers

Shrub

Korean Rhododendron
Rhododendron mucronulatum

Korean Rhododendron flowers
Korean Rhododendron flowers
 
Features
Showy light purple to rosy pink flowers in early to mid spring; leaves are deciduous (shed in autumn), but they turn yellow and bronze before falling. 
 
Culture
Partial to full shade; moist, well-drained soil is best; needs acid soil. 
 
Cultivars
  • 'Cornell Pink'- Pink flowers.
  • 'Crater's Edge' - Dark red buds opening to lavender pink flowers.

Common Groups of Hybrid Rhododendrons

'Girard' Hybrids: This large group of azaleas includes both deciduous and evergreen cultivars. They vary in flower color and winter hardiness.

'Knapp Hill' Hybrids: The result of crosssing several species of Rhododendron. A large group including 'Knapp Hill', 'Exbury', 'Slocock' and 'Ilam' Hybrids. These azaleas are deciduous. Flower color depends on the cultivar selected. Mildew can be a problem with this group. hardiness zone 5-7.

'Northern Lights' Hybrids: Developed at University of Minnesota. These hybrids were selected for excellent cold hardiness (to -30 degrees). These azaleas are deciduous. Flower color depends on cultivar selected.

'P.J.M.' Hybrids:A group of hybrids that are known for their compact size (3-6 ffet) and their flower color (shades of lavender pink to mauve). These rhododendrons are evergreen, with the foliage taking on a purplish cast in winter. Hardy zone 5 to 7.

 
 
Mature Height
3-6 Feet
 
Size
Small
 
 
Mature Width
3-6 Feet
 
Mature Form
Oval to rounded 
 
Native To:
China, Korea and Japan 
 
USDA Hardiness Zone
5 - 7 
 
Soil Conditions
Moist, Well-Drained
 
 
Tolerance
 
 
Exposure/Light Requirements
Full Shade
Partial Sun/Shade
 
 
Uses
Border
Foundation
Specimen
 
 
Foliage Color
Green
 
 
Fall Foliage Color
Yellow
 
 
Pests and Problems
 
Additional Notes
Alkaline soils will lead to chlorosis (yellowing) of the leaves.

 

 
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