About
Rhododendron simsii, the Indian azalea, is a tender evergreen or semi-evergreen azalea to 2 m with a branching habit and broadly ovate leaves. Funnel-shaped, carmine to rich-red flowers with darker spots appear in pairs or small clusters at the stem tips in late spring. A parent of many Indica hybrids and a popular conservatory plant.
About the genus
Rhododendron, the rhododendrons and azaleas, are a vast genus of evergreen and deciduous shrubs and trees producing simple leaves � sometimes with a dense, colourful indumentum beneath � and funnel-shaped, bell-shaped or tubular flowers in a wide range of colours in spring and early summer. They thrive in moist, acid, humus-rich, well-drained soil in dappled shade.
Growing conditions
SunlightPartial shade
Soil typeClay, Loam, Sand
Soil pHAcid
Soil moistureMoist but well-drained
AspectNorth-facing, West-facing
ExposureSheltered
UK hardinessH4
Plant details
Plant typeShrubs
HabitSpreading branched
FoliageEvergreen, Semi evergreen
Height1.5-2.5 metres
Spread1.5-2.5 metres
Time to full height5-10 years
Suggested usesCity and courtyard gardens, Cottage and informal garden, Patio and container plants
Native toBurma, Thailand, 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
CultivationMay be grown outdoors in frost free areas, otherwise best grown under glass or in containers that can be moved indoors over winter. Grow in moist but well-drained, humus rich, acidic soil or in an ericaceous potting mix, and position in partial or dappled shade. See rhododendron cultivation for more detailed advice
PruningGenerally requires minimal pruning, though may need restrictive pruning if grown under glass; see pruning group 8 (evergreens). Deadhead if practical, to promote vegetative growth rather than seed production
PropagationPropagate by semi-ripe cuttings in late summer, or by grafting in 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 powdery mildews, honey fungus, silver leaf and Phytophthora, as well as more specific Rhododendron diseases