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ShrubsSynonym

Azalea obtusa

rhododendron Obtusum Group

A variable group of evergreen shrubs, usually to about 1m high, and densely branched with bristly shoots and small, glossy green leaves. Free-flowering, producing clusters of funnel-shaped reddish purple or sometimes white flowers, in mid to late spring

Synonyms

Rhododendron obtusum
Azalea obtusa

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Ultimate height

0.5–1 metres

Time to ultimate height

10–20 years

Ultimate spread

1–1.5 metres

Clay

Loam

Sand

Moisture

Moist but well–drained

pH

Acid

	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Partial shade

Aspect

East–facing or North–facing or West–facing

Exposure

Sheltered

Hardiness
Hardiness ratings
All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets
H1a: under glass all year (>15C)
H1b: can be grown outside in the summer (10 - 15)
H1c: can be grown outside in the summer (5 - 10)
H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
H4: hardy through most of the UK (-10 to -5)
H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
H6: hardy in all of UK and northern Europe (-20 to -15)
H7: hardy in the severest European continental climates (< -20)

Botanical details

Family: Ericaceae
Native to GB / Ireland: No
Foliage: Evergreen
Habit: Bushy
Potentially harmful: Harmful 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
Genus: Rhododendron can be evergreen or deciduous shrubs or trees, with simple leaves, sometimes with a dense colourful indumentum of hairs on the lower side, and funnel-shaped, bell-shaped or tubular flowers that may be solitary or in short racemes
Name status: Accepted
Horticultural Group: Evergreen azaleas are compact evergreen shrubs with small leaves and terminal racemes of small, funnel-shaped, usually unscented flowers in early summer

How to grow

Cultivation

Grow in moist but well-drained, humus rich, acidic soil, in partial or dappled shade. Choose a site away from frost pockets and sheltered from strong winds, and do not allow plants to dry out. Mulch annually, ideally with leaf mould. See rhododendron cultivation for more detailed advice

Propagation

Propagate by semi-ripe cuttings in late summer, or by grafting in winter

Suggested planting locations and garden types

City and courtyard gardens
Cottage and informal garden
Patio and container plants
Low Maintenance
Flower borders and beds

Pruning

Minimal pruning required, see pruning group 8 (evergreens)

Pests

May be susceptible to vine weevil, rhododendron and azalea whitefly, rhododendron leafhopper, Pieris lacebug, scale insects, caterpillars and aphids

Diseases

May be susceptible to powdery mildews, honey fungus, silver leaf and Phytophthora, as well as more specific Rhododendron diseases

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