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Rhododendron viscosum (Vs)
  • RHS AGM

swamp azalea

R. viscosum is a bushy deciduous shrub to 2.5m tall, with dark leaves glaucous beneath. Very fragrant, narrowly funnel-shaped white flowers, up to 4cm wide, flushed deep pink on the tube, open in early to mid summer

Other common names
swamp honeysuckle
white swamp honeysuckle
Synonyms
Rhododendron oblongifolium
Azalea viscosa L.
see moreRhododendron serrulatum

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Size
Ultimate height
1.5–2.5 metres
Time to ultimate height
10–20 years
Ultimate spread
1.5–2.5 metres
Growing conditions
Clay
Loam
Sand
Moisture
Moist but well–drained
pH
Acid
Colour & scent
StemFlowerFoliageFruit
Spring Blue Green
Summer Pink White Blue Green
Autumn
Winter
Position
  • Full sun
  • Partial shade
Aspect

South–facing or East–facing or West–facing

Exposure
Sheltered
Hardiness
H6
Botanical details
Family
Ericaceae
Native to the UK
No
Foliage
Deciduous
Habit
Bushy
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

Horticultural Group
Viscosa azaleas are lax deciduous shrubs with fairly small leaves and trusses of funnel-shaped, fragrant flowers in early summer
Plant range
Eastern N America

How to grow

Cultivation

Grow in moist but well-drained, leafy, humus-rich acid soil in part shade with shelter; sun tolerant if soil remains reliably moist; see rhododendron cultivation

Propagation

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

Suggested planting locations and garden types
  • City and courtyard gardens
  • Cottage and informal garden
  • Flower borders and beds
Pruning

Pruning group 1

Pests

May be attacked by vine weevil, rhododendron leafhopper, pieris lacebug, scale insects, caterpillars and aphids

Diseases

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

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