Rhododendron maddenii subsp. crassum

Common Name: rhododendron 
Type: Broadleaf evergreen
Family: Ericaceae
Native Range: Himalayas, Indochina
Zone: 8 to 10
Height: 3.00 to 6.00 feet
Spread: 3.00 to 6.00 feet
Bloom Time: May to June
Bloom Description: White flushed with purple
Sun: Part shade to full shade
Water: Medium
Maintenance: Medium
Flower: Showy, Fragrant
Leaf: Evergreen
Other: Winter Interest
Tolerate: Rabbit, Heavy Shade

Culture

Winter hardy to USDA Zones 8-10 where it is best grown in acidic, humusy, organically rich, moisture-retentive but well-drained soils in part shade. Winter hardy to 10-15 degrees F., but may lose flower buds in such temperatures. Prefers a sun dappled shade. Tolerates heat and sun better than many of the rhododendrons. Acidify soils prior to planting and thereafter as needed. Plant in a location protected from strong winter winds. Good soil drainage is essential (doesn’t like “wet feet”). Poor drainage inevitably leads to root rot, therefore raised beds/plantings should be considered in areas with heavy clay soils. Shallow, fibrous root systems (do not cultivate around plants) will benefit greatly from a mulch (e.g., wood chips, bark or pine needles) to help retain moisture and stabilize soil temperatures. Roots must never be allowed to dry out.

Noteworthy Characteristics

Rhododendron maddenii subsp. crassum is a generally upright evergreen shrub that is native to forested areas, thickets, ridges and slopes from the Himalayas to southern China (Yunnan) south to Myanmar, Thailand and Vietnam. It typically grows to 6' tall over the first 10 years. In its native habitat, it will grow over time to as much as 25-30' tall (plants generally grow taller in shaded areas than open sunny areas). Elliptic to lanceolate, medium to dark green leaves (to 7" long) are evergreen. Fragrant, tubular, funnel-shaped, white flowers (each to 4" wide) bloom in late spring in trusses of 3-10. Flowers are frequently flushed with purple. Rhododendron maddenii was reportedly discovered by Joseph Hooker in 1849 in the Sikkim Himalayas (northern India). R. maddenii subsp. crassum was reportedly discovered in the Tali mountains in Yunnan province of China in 1885 and subsequently described by Franchet in 1887.

Genus name comes from the Greek words rhodo meaning rose and dendron meaning tree. Transferred from the Greek name for Nerium oleander.

Specific epithet honors Edward Madden of the Bengal Civil Service.

Problems

Rhododendrons are susceptible to many insect and disease problems, including but not limited to canker, crown rot, root rot, leaf spot, rust, powdery mildew, aphids, borers, lacebugs, leafhoppers, mealybugs, mites, nematodes, scale, thrips and whitefly. A healthy plant in the proper environment with proper care should have limited problems, however.

Garden Uses

Where winter hardy, this rhododendron fits well into woodland gardens, woodland areas and other shady or sun-dappled areas of the landscape.