Allium 'Mont Blanc'

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allium 'Mont Blanc'

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allium 'Mont Blanc' RHS / Joanna Kossak
allium 'Mont Blanc' RHS / Joanna Kossak
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Tall, bulbous perennial to about 1m with broad, greyish-green, strap-shaped leaves that die back as the flowers open. Star-shaped flowers, white with a hint of green, are carried in dense, spherical heads in late spring and early summer

Position

Full sun

Soil Types

Chalk, Clay, Loam, Sand

Max Height

0.5-1 metres

Max Spread

0.1-0.5 metres

Size

Time to Maturity
2–5 years
Max Spread
0.1-0.5 metres
Max Height
0.5-1 metres

Growing Conditions

Chalk Clay Loam Sand
Moisture
Moist but well–drained or Well–drained
pH
Acid or Alkaline or Neutral

Position

Full sun
Aspect
South–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

Fragrance Foliage
Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Amaryllidaceae
Native to GB/Ireland
No
Foliage
Deciduous
Habit
Columnar upright
Genus
Allium are bulbous herbaceous perennials with a strong onion or garlic scent, linear, strap-shaped or cylindrical basal leaves and star-shaped or bell-shaped flowers in an umbel on a leafless stem
Name Status
Accepted

How to Grow

Cultivation

Grow in fertile, well-drained soil. Add grit to clay soils to improve drainage. See allium cultivation

Propagation

Propagate by removing offsets in autumn

Suggested planting locations and garden types

  • Architectural
  • City and courtyard gardens
  • Cottage and informal garden
  • Gravel garden
  • Wildlife gardens
  • Cut flowers
  • Flower borders and beds

Pruning

No pruning required

Pests

Generally pest-free

Diseases

Generally disease-free but may be susceptible to onion white rot and downy mildews