Northwest Blooms · Shrubs
Rhododendron x molle ‘Koster’s Brilliant Red’
Koster's Brilliant Red Azalea
- Family
- Ericaceae
- Height
- 3 to 5 ft
- Width
- 3 to 5 ft
- Flower color
- Reddish-orange clusters, often with red spotting on the upper petals
- Foliage color
- Deciduous medium green leaves with orange-red to bronze-red fall color
- Bloom time
- Late spring to early summer
- Light
- Full sun to part shade
- Water
- Moderate
- Maintenance
- Low; prune lightly only if shaping is needed
- Growing zone
- USDA zones 5 to 8
- Wildlife
- Flowers attract pollinators
About this plant
Rhododendron x molle 'Koster's Brilliant Red' is a deciduous azalea that blooms in late spring, often May into June, with clustered trumpet-shaped flowers in reddish-orange to scarlet tones. The upper petals commonly show small red spots, and the blossoms open as the fresh green leaves expand. Flowers are sometimes lightly fragrant on warm, still spring days, followed by orange-red autumn color.
Raised in Holland by Koster & Sons and introduced in 1918, the name originally covered uniform seedlings repeatedly produced from the same cross, so plants sold under it can show slight variation. It remains valued for its late-spring trusses and warm flower color in woodland borders and mixed shrub plantings.
Works well in
Sun Gardens · Borders · Cottage Gardens · Containers
Companion plants
Poppies · Milkweed · Bee balm · Feather reed grass · Rock cress · Alpine mint bush
Design tip
Thread ‘Koster’s Brilliant Red’ through a mixed shrub planting rather than isolating it as a single specimen, allowing its fiery spring color to appear in several places. The repetition draws the eye through the garden and strengthens its later autumn display.
