Common Name: Korean azalea
Type: Deciduous shrub
Family: Ericaceae
Native Range: Southern and central Korea
Zone: 4 to 9
Height: 3.00 to 6.00 feet
Spread: 6.00 to 12.00 feet
Bloom Time: April to May
Bloom Description: Rose-purple
Sun: Part shade to full shade
Water: Medium
Maintenance: Medium
Suggested Use: Hedge
Flower: Showy, Fragrant
Attracts: Hummingbirds, Butterflies
Tolerate: Rabbit
Culture
Best grown in acidic, humusy, organically rich, medium moisture, moisture-retentive but well-drained soils in part shade to full shade. Plant in a location protected from strong winter winds. Good soil drainage is essential (doesn't like "wet feet"). Poor drainage can cause root rot, therefore raised plantings should be considered in heavy clay soils. Shallow root system (avoid cultivating around shrub) will benefit greatly from a good organic mulch (e.g., bark, oak leaves or pine needles) to retain moisture and to stabilize soil temperatures. Roots must not be allowed to dry out.
Noteworthy Characteristics
Rhododendron yedoense var. poukhanense, a Korean azalea, is a spreading, low to medium sized shrub which typically grows 3-6' tall with an 8-12' spread. Evergreen in mild winters, but deciduous in cold winter climates. Dark green foliage turns an attractive orange-red in autumn. Lavender to rose purple, slightly fragrant, 2" wide flowers, each with a darker blotch, appear in trusses of 2-4 flowers each in early spring (April-May in the St. Louis area). An important parent in the development of many of the hybrid evergreen azaleas in commerce today.
Genus name comes from the Greek words rhodo meaning rose and dendron meaning tree. Transferred from the Greek name for Nerium oleander.
Specific epithet means of Yedo (now Tokyo), Japan.
Problems
Rhododendrons and azaleas are susceptible to many insect and disease pests, including but not limited to canker, crown rot, root rot, leaf spot, rust, powdery mildew, aphids, borers, lacebugs, leafhoppers, mealy bugs, mites, nematodes, scale, thrips and whitefly. A healthy plant in the proper environment in good soil with proper care should have limited problems, however. This Korean azalea reportedly has good resistance to root rot.
Uses
Mass or group in shrub or mixed borders or woodland gardens. Good specimen value. Also effective as a foundation planting.