Hiryu Azalea Rhododendron ponticum

Kurume azalea is a woody, dwarf, broadleaf evergreen or deciduous shrub in the Ericaceae (blueberry) family that is dense, spreading, and grows 3 to 4 feet tall and 2 to 5 feet wide. It is native to Bulgaria, Lebanon, and the Caucasus. The genus name derives from the Greek words rhodo, which means rose, and dendron, meaning tree.  

This plant prefers partial shade with protection from afternoon sun, which can scorch the leaves. Grow it in acidic, moist but well-drained soils. Plant the root ball high in the soil to help with drainage issues. It is intolerant of heavy and wet soils, drought, and excessive fertilization. It has a slow growth rate and requires a high level of maintenance. Pruning, if desired, may be done after flowering.

This plant is a very common spring blooming azalea with hundreds of cultivars. It blooms in mid spring, usually 1 to 2 weeks before R. indicum. The persistent evergreen leaves are smaller than the seasonal deciduous leaves. 

Grow this azalea as a mass planting in a shrub border, a foundation planting, or a specimen in a woodland or pollinator garden where the flowers will attract hummingbirds and bees. This plant is also used in bonsai. 

Quick ID Hints:

• Dwarf semigreen shrub with sympodial growth, crowded leaves
• Twigs and leaves with reddish-brown hairs
• Flowers axillary, solitary, in spring with a funnel form
• Flowers hose-in-hose, single or double
• Calyx lobes short, broad, obtuse

Insects, Diseases, and Other Plant Problems:  Insect problems include aphids, borers, lace bugs, leafhoppers, mealybugs, mites, nematodes, scale, thrips, and whitefly. Diseases include canker, crown rot, root rot, leaf spot, rust, and powdery mildew. This plant is frequently damaged by deer. 

While rhododendrons remain very popular for landscape use, many cultivars are susceptible to Phytophthora root rot—this leads to leaf loss, reduced vigor, branch dieback, and wilting. Implement good cultural practices first, such as improving drainage with organic matter or berms and avoiding overwatering or overfertilization. For suitable alternatives, see this video created by Charlotte Glen as part of the Plants, Pests, and Pathogens series.

VIDEO Created by Elizabeth Meyer for "Trees, Shrubs and Conifers" a plant identification course offered in partnership with Longwood Gardens.

More information on Rhododendron.