About
Rhododendron rex subsp. rex, the king rhododendron, is the typical subspecies: a very large evergreen shrub or small tree with broadly obovate, glossy dark-green leaves with buff indumentum beneath and trusses of bell-shaped, white or pink flowers blotched crimson at the base in mid to late spring. A majestic specimen for a sheltered, moist, acidic garden in a mild climate.
About the genus
Rhododendron, one of the largest and most diverse shrub genera, includes evergreen and deciduous species and hybrids ranging from dwarf alpines to large trees, all preferring moist, well-drained, acidic soil in sheltered positions with dappled shade or full sun.
Growing conditions
SunlightPartial shade
Soil typeClay, Loam, Sand
Soil pHAcid
Soil moistureMoist but well-drained
AspectWest-facing, South-facing, East-facing
ExposureSheltered
UK hardinessH5
Plant details
Plant typeShrubs
HabitBushy
FoliageEvergreen
Height8-12 metres
Spread4-8 metres
Time to full height10-20 years
Suggested usesArchitectural, Cottage and informal garden
Native toSW China
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, best in light woodland conditions; see rhododendron cultivation
PruningPruning group 8
PropagationPropagate by 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