Rhododendron griersonianum

Rhododendron griersonianum is an evergreen shrub in the heath family, Ericaceae. Its native range runs from western Yunnan, China, into northeastern Myanmar. It grows in conifer woods, mixed woods, and scrub. PFAF records wild sites at 7,054–8,858 feet [2,150–2,700 metres]. It is not native to Britain or Ireland.

This bushy shrub reaches about 10 feet [3 metres] tall. The RHS gives a garden height range of 8–13 feet [2.5–4 metres]. Its listed spread spans the same range. Plants take 10–20 years to reach their full size. Young shoots carry a thick coat of woolly hairs. The oval leaves are olive green above, with brown felt beneath. They stay on the plant through winter. Long buds taper to a point before they open. Bright red flowers appear in late spring and early summer. Each cluster can hold up to 12 blooms. Their shape ranges from a tube to a bell.

Grow this shrub in acid soil rich in humus. The soil should hold moisture but let excess water drain. The RHS lists clay, loam, and sand as suitable soils. Choose full sun or a spot with light shade. Shelter the plant from strong winds and avoid frost pockets. Add mulch each year; the RHS suggests leaf mould. Its RHS hardiness rating is H5. PFAF lists USDA zones 7–10. These ratings describe hardiness under different systems and growing conditions.

Use it in woodland gardens, at shady edges, or in borders. The RHS also suggests cottage gardens and beds beside walls. PFAF lists it as a hedge plant that accepts trimming. Otherwise, it needs little pruning. Take semi-ripe cuttings in late summer to raise new plants. Winter grafting offers another way to propagate it. Its evergreen leaves and red flower clusters give it garden value.

Watch for vine weevils, whiteflies, leafhoppers, and Pieris lacebug. Scale insects, aphids, and caterpillars may also attack it. Possible diseases include powdery mildew, honey fungus, silver leaf, and Phytophthora. The RHS warns that eating this plant harms people and pets. It also advises gloves and other protection when handling it. PFAF records no known food or medicinal uses. Do not treat the lack of recorded uses as evidence of safety.