About
Rhododendron arboreum, tree-like rhododendron, is a large, narrow evergreen tree with dark green leaves to 20 cm, bearing cinnamon-brown, fawn or silvery indumentum beneath. In early spring it produces rounded trusses of funnel-shaped flowers to 5 cm, in red, pink or white � one of the most spectacular of all wild rhododendrons.
About the genus
Rhododendron are evergreen or deciduous shrubs and trees with simple leaves and funnel-shaped, bell-shaped or tubular flowers � solitary or in short racemes � in a vast range of colours. They include azaleas and are essential shrubs for sheltered, moist, acid-soil woodland gardens.
Growing conditions
SunlightPartial shade
Soil typeLoam, Sand
Soil pHAcid
Soil moistureMoist but well-drained
AspectSouth-facing, North-facing, West-facing, East-facing
ExposureSheltered
UK hardinessH4
Plant details
Plant typeTrees
HabitColumnar upright
FoliageEvergreen
Height8-12 metres
Spread2.5-4 metres
Time to full height20-50 years
Suggested usesArchitectural, Cottage and informal garden
Native toIndia & Sino-Himalaya
ToxicityHarmful if eaten. Wear gloves and other protective equipment when handling. Pets (dogs, cats, rabbits, tortoises) Harmful if eaten - for further information and contact numbers regarding pets, see the HTA guide to potentially harmful plants
Care notes
CultivationGrow in moist but well-drained, leafy, humus-rich acid soil in part shade with shelter; see rhododendron cultivation
PruningPruning group 8
PropagationPropagate by seed when ripe, or semi-ripe cuttings in late summer, layering in autumn or grafting in late summer or late winter
Pest resistanceMay be susceptible to vine weevil, rhododendron and azalea whitefly, rhododendron leafhopper, pieris lacebug, scale insects, caterpillars and aphids
Disease resistanceMay be susceptible to various Rhododendron diseases including powdery mildews, rhododendron petal blight, rhododendron bud blast, silver leaf and honey fungus