Centaurea simplicicaulis

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unbranched-stemmed knapweed

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Synonyms

Centaurea simplicicaulis

Plants for pollinators
Herbaceous Perennial
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A compact, clump-forming alpine perennial to around 30cm high, with divided, lobed green leaves with a fine down giving a silvery appearance. Flowers appear from late spring to mid summer, producing buds encased in overlapping white-tipped bracts, which open to showy, pale mauve-pink flowers

Position

Full sun

Soil Types

Chalk, 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 Loam Sand
Moisture
Well–drained
pH
Acid or Alkaline or Neutral

Position

Full sun
Aspect
South–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
Drought Resistance
Yes

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Asteraceae
Native to GB/Ireland
No
Foliage
Deciduous
Habit
Clump forming
Genus
A genus of clump-forming, often woody herbaceous perennials with grey-green dissected leaves and showy pink, purple or white flowers
Name Status
Synonym
Plant Range
Turkey, Transcaucasus

How to Grow

Cultivation

Grow in almost any well-drained soil in full sun. Thrives in poor soils but will not tolerate waterlogging

Propagation

Propagate by seed or by division, separating rhizomes in autumn

Suggested planting locations and garden types

  • Coastal
  • Cottage and informal garden
  • Gravel garden
  • Mediterranean climate plants
  • Rock garden
  • Wildflower meadow
  • Wildlife gardens
  • Banks and slopes
  • Flower borders and beds

Pruning

deadhead to encourage more flowers, unless seed is required

Pests

Generally pest-free

Diseases

May be susceptible to downy mildews, Powdery mildews and rust diseases