Centaurea montana 'Alba'

RHS Plant Profile
white perennial cornflower

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A rhizomatous perennial about 45cm tall, forming a mat of undivided grey-green leaves, and woolly stems bearing white flower-heads, often tinged pink, in late spring and early summer

Position

Full sun, Partial shade

Soil Types

Chalk, Clay, Loam, Sand

Max Height

0.1-0.5 metres

Max Spread

0.1-0.5 metres

Size

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

Growing Conditions

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

Position

Full sun Partial shade
Aspect
South–facing or East–facing or West–facing
Exposure
Exposed or 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)
H7

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Asteraceae
Native to GB/Ireland
No
Foliage
Deciduous
Habit
Bushy
Genus
Centaurea may be annuals, perennials or subshrubs, with simple or pinnately lobed leaves and showy thistle-like flowers-heads, often with enlarged outer florets
Name Status
Accepted

How to Grow

Cultivation

Grow in moist but well-drained soil in full sun or partial shade

Propagation

Insert root cuttings in winter or propagate by division in spring. Propagate by seed, self sown seedling come fairly true

Suggested planting locations and garden types

  • Coastal
  • Cottage and informal garden
  • Patio and container plants
  • Wildlife gardens
  • Flower borders and beds
  • Cut flowers

Pruning

Deadhead to prolong flowering and cut back to encourage fresh foliage

Pests

Generally pest-free

Diseases

Powdery mildews and downy mildew may be a problem