1 / 5

Key characteristics

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

Shrubs

Rhododendron occidentale 'Irene Koster'

Irene Koster Rhododendron

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.

Light

Full sun to part shade

Water

Moderate

Bloom time

Late spring to early summer

Find this plant

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.

Printable plant sheet (PDF)