Rhododendron mucronulatum aka Rhododendron

Rhododendron mucronulatum is a deciduous shrub called Korean rosebay. It belongs to the heath family, Ericaceae. Its native range spans the Russian Far East, China, Korea, and Japan. It grows slowly and sheds its leaves each year. Garden plants reach about 4–8 feet [1.2–2.4 metres] tall and wide. RHS gives an upper size of 8.2 feet [2.5 metres]. Plants may take 10–20 years to reach full size.

Several stems form an open, upright shrub with a rounded outline. The bark is smooth and pale brown. Yellow dots, like small resin marks, cover the twigs. The green leaves grow in an alternate pattern along them. Each leaf is narrow, with an oval or lance-like shape. The undersides bear scales, and crushed leaves give off a scent. Fall brings yellow, orange, bronze, and wine-red tones. This color change comes later than on many other plants.

Flowers open before the leaves, from late winter into early spring. UConn and Chicago report bloom around early April. The funnel-shaped blooms range from pink to pale rosy purple. RHS also records white flowers within the species. Flowers appear alone or in small groups near branch tips. Each bloom measures about 0.13–0.17 feet [0.04–0.05 metres] across. Bees and hummingbirds visit the flowers. Small capsules follow the blooms and split open when ripe. The fruit and bark add little to its garden display.

Grow this shrub in moist, acidic soil with good drainage. Soil rich in organic matter suits it best. It grows in sun or light shade. NCSU favors dappled shade and shelter from hot afternoon sun. Strong sun can scorch the leaves. Avoid frost pockets and sites exposed to strong winds. Annual mulch helps keep the roots cool. Prune lightly once flowering ends. Sources place it in USDA zones 4–7, with NCSU extending to 8. RHS rates its cold hardiness H6. Late frosts can still damage the early flowers.

Use it in shrub borders, woodland groups, or as a specimen. It also suits hedges, screens, and planting near house foundations. Early flowers and late fall color provide two seasons of interest. Deer often damage this shrub. Aphids, borers, lacebugs, scale, and whitefly may also cause trouble. Diseases include mildew, leaf spot, canker, and root rot. Wet, heavy soil raises the risk of Phytophthora root rot. High soil pH can cause chlorosis. PFAF lists raw flower petals as edible, but advises caution. RHS warns that eating this plant can harm people and pets. Its reported food use does not establish that eating it is safe.