Rhododendron 'Shamrock'

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rhododendron 'Shamrock'

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rhododendron 'Shamrock' RHS / Joanna Kossak
rhododendron 'Shamrock' RHS / Joanna Kossak
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'Shamrock' is a compact, dwarf, spreading shrub up to 75cm high and wide with small evergreen leaves and many trusses of from five to nine funnel-shaped, pale yellow flowers, 0.7-2.5cm across, tinged green and spotted yellow inside, in early and mid-spring

Position

Full sun, Partial shade

Soil Types

Clay, Loam, Sand

Max Height

0.5-1 metres

Max Spread

0.5-1 metres

Size

Time to Maturity
5–10 years
Max Spread
0.5-1 metres
Max Height
0.5-1 metres

Growing Conditions

Clay Loam Sand
Moisture
Moist but well–drained
pH
Acid

Position

Full sun Partial shade
Aspect
North–facing or South–facing or West–facing or East–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)
H6

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Ericaceae
Native to GB/Ireland
No
Foliage
Evergreen
Habit
Spreading branched
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

How to Grow

Cultivation

Grow in light dappled shade, in a site sheltered from cold, dry winds and late frosts, in moist but well-drained, humus-rich, acidic soil, preferably between pH4.5 and pH5.5; will also tolerate sun and dry soil; for more advice, see rhododendron cultivation

Propagation

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

Suggested planting locations and garden types

  • City and courtyard gardens
  • Cottage and informal garden
  • Low Maintenance
  • Banks and slopes
  • Flower borders and beds

Pruning

Pruning group 1 (little or no pruning of trees and shrubs) or pruning group 8 (early-flowering evergreen shrubs)

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