Northwest Blooms · Shrubs
Rhododendron occidentale 'Irene Koster'
Irene Koster Rhododendron
- Family
- Ericaceae
- Height
- 6 to 8 ft
- Width
- 4 to 6 ft
- Flower color
- Fragrant pale pink to light rose-pink blooms with yellow-gold blotches and subtle orange spotting
- Foliage color
- Deciduous green leaves that may exhibit autumn color before dropping
- Bloom time
- Late spring to early summer
- Light
- Full sun to part shade
- Water
- Moderate
- Maintenance
- Low to moderate; little pruning needed beyond removing spent flowers
- Growing zone
- USDA zones 5 to 9
- Wildlife
- Flowers attract bees and other pollinators, including hummingbirds
About this plant
Rhododendron occidentale 'Irene Koster' is a deciduous azalea with fresh green leaves and a graceful, airy look in the growing season. In late spring, very fragrant, tubular funnel-shaped flowers open from buds marked with darker pink striping. The blooms are white to light rose-pink, highlighted by a showy yellow blotch and warm orange-brown spotting on the upper petals.
Introduced by Koster & Sons of Holland around the late 1800's as part of the Occidentale hybrid group, 'Irene Koster' has remained popular for its perfume and generous spring bloom. Its flowers suit woodland borders, mixed shrub plantings, and areas near paths or seating where the fragrance can be enjoyed.
Works well in
Sun Gardens · Foundation Plantings · Fragrant Gardens · Hummingbird Gardens
Companion plants
Camas · Mexican orange blossom · Bee balm · Maiden grass · Sea thrift · Flowering quince
Design tip
Bring ‘Irene Koster’ close to a patio, entry, or garden path where its strong fragrance becomes part of the spring experience. Its airy deciduous form also pairs naturally with denser evergreens, preventing a larger shrub grouping from feeling overly solid or heavy.
