Sign up for our newsletter
Gardening in the Rainy Zone.
Pronounced: ro-do-DEN-dron or-bik-ew-LAH-ree
Sunset zones: Not listed.
USDA zones: 7-9.
Heat zones: 9-7.
Height: 3-6 feet (1-2 m) in 10 years. Can reach up to 20 feet (5 m) over time.
April to May.
Loose trusses carry 7-10 pink flowers that are widely campanulate (bell-shaped) and 2 1/2 inches across.
4-inch long, midgreen, ovate to orbicular leaves are held on the stems with purple petioles. The leaves are almost as wide as they are long.
Full sun to part shade.
Humus rich, well-drained, acidic soil.
Lightly prune for symmetry after the shrub has finished flowering; rarely needs pruning.
Rainy Side Notes
Rhododendrons are so commonly grown here in the Pacific Northwest that sometimes we take a ho-hum attitude--if you've seen one you've seen them all. However, Rhododendron orbiculare comes along with its untypical rhododendron foliage that its epithet, orbiculare, describes--rounded leaves. In spring, the leaves take a back seat to trusses carrying the hanging, bell-shaped, pink flowers that profusely cover the shrub.
Orbiculare originally comes from the forests and rocky slopes of Guangxi and Sichuan in China. It grows best in full sun; the shrub grows leggy in the shade. The Royal Horticulture Dictionary claims these shrubs can eventually reach 50 feet (15 m) over time. Was that a typo, or is there an actual specimen that large? The shrub grows wider than it is tall. Most likely, in your Northwest garden it will ultimately reach 20 x 20 feet. Prune if you live to see it grow beyond that point, or there goes the neighborhood.
Photographed at the Rhododendron Species Foundation Garden.