Common Name: rhododendron
Type: Broadleaf evergreen
Family: Ericaceae
Native Range: Southwestern China
Zone: 8 to 10
Height: 20.00 to 35.00 feet
Spread: 15.00 to 30.00 feet
Bloom Time: April
Bloom Description: Creamy white to pale yellow
Sun: Part shade to full shade
Water: Medium
Maintenance: Medium
Flower: Showy
Leaf: Evergreen
Other: Winter Interest
Tolerate: Rabbit
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. Prefers a sun dappled shade. Foliage may scorch in full sun. 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. Clip off spent flower clusters immediately after bloom as practicable. This rhododendron is not winter hardy to the St. Louis area.
Noteworthy Characteristics
Rhododendron sinogrande is an evergreen understory tree or large shrub that is native to coniferous forests in alpine areas of western China, Tibet and Burma. In its native habitat, it will grow to as much as 50' tall. Everything about this plant is big, including its glossy dark green leaves which grow to as much as 3' long and its creamy white to pale yellow flowers (to 3" wide) which bloom in trusses of 15-30 flowers in spring. The underside of leaves are pale brown to silvery white. Leaves are reportedly the largest found on any rhododendron.
Genus name comes from the Greek words rhodo meaning rose and dendron meaning tree. Transferred from the Greek name for Nerium oleander.
Specific epithet comes from sino meaning about China and grande meaning showy.
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.
Uses
Where winter hardy, this rhododendron fits well into woodland gardens, woodland areas and other shady parts of the landscape.