Rhododendron ferrugineum aka Rhododendron

Rhododendron ferrugineum, or alpine rose, belongs to the heath family, Ericaceae. This evergreen shrub comes from the mountains of Europe. Its native range includes the Pyrenees and eastern France. It extends to the northwestern Balkans and Poland's Karkonosze Mountains. It grows on mountain slopes, in open woods and scrub. It can dominate the low shrub zone in these habitats. It is not native to Britain or Ireland.

In gardens, it forms a small bush with spreading branches. Its height and width reach about 1.6–3.3 feet [0.5–1 metre]. It takes 10–20 years to reach its full size. The leaves stay on the plant through winter. Their upper sides are dark green and glossy. Rust-brown scales coat the undersides, giving them a contrasting colour. In June, small clusters of tube-shaped flowers open. Most flowers range from rose pink to deep crimson. White flowers also occur, though they are less frequent.

Grow it in acid soil with plenty of humus. It accepts loam, clay or sand where drainage is good. Keep the soil moist, but do not leave it waterlogged. Both full sun and partial shade suit this shrub. Avoid sites where walls or paving reflect too much heat. The RHS rates its winter hardiness as H6. This covers minimum temperatures of about −20 to −15°C. Plants For A Future lists USDA zones 4–8. Take semi-ripe cuttings in late summer to raise new plants.

Its low, spreading form suits beds and informal gardens. It also fits containers and woodland edges with dappled shade. Gardeners can use it as ground cover. For this use, space plants about 3.3 feet [1 metre] apart. Its leaves give year-round cover, while June brings flower colour. Several pests may attack it, including vine weevil and rhododendron leafhopper. Other risks include pieris lacebug, scale insects, caterpillars and aphids. Diseases include powdery mildew, petal blight and bud blast. Silver leaf and honey fungus may also occur.

Do not eat this plant or treat it as food. Its leaves and galls are poisonous; no edible uses are known. The RHS also warns that eating it can harm pets. Wear gloves and other protective gear when handling it. Records describe medicinal use for arthritis and rheumatism. Such use can cause vomiting and diarrhoea and needs expert supervision. Some plant compounds have shown activity against other plants. This finding needs more research before any practical herbicide use.