Rhododendron yakushimanum

RHS Plant Profile

Yakushima rhododendron

Synonyms

Rhododendron yakushimanum montanum 'Alpina'
Rhododendron metternichii var. yakushimanum
Rhododendron degronianum subsp. yakushimanum

Shrubs

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A compact, spreading evergreen shrub with narrow, convex leaves with a buff-felt beneath, and rounded trusses of bell-shaped, pure white flowers, opening from bright pink buds in mid spring. Shortlisted for Chelsea Plant of the Centenary in 2013 for the decade 1943-1952

Position

Full sun, Partial shade

Soil Types

Clay, Loam, Sand

Max Height

1-1.5 metres

Max Spread

1-1.5 metres

Size

Time to Maturity: 10–20 years
Max Spread: 1-1.5 metres
Max Height: 1-1.5 metres

Growing Conditions

Clay Loam Sand

Moisture: Moist but well–drained
pH: Acid

Position

Full sun Partial shade

Aspect: South–facing or East–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): H5

Colour & Scent

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

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: Correct
Plant Range: Japan

How to Grow

Cultivation

Grow in moist but well-drained, leafy humus-rich, acid soil. Shallow planting is essential, deep planting will not be tolerated. See rhododendron cultivation

Propagation

Propagate by seed, semi-hardwood cuttings in late summer, layering in autumn or grafting in late summer or late winter

Suggested planting locations and garden types

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

Pruning

Pruning group 8

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 various Rhododendron diseases including powdery mildews, rhododendron petal blight, rhododendron bud blast, silver leaf and honey fungus