Alphabetical Plant Listing

Centaurea macrocephala (Giant Knapweed)

Giant Knapweed, Great-Headed Centaury, Bighead Knapweed, Big Yellow Centaurea, Lemon Fluff, Yellow Bachelor's Button, Yellow Hardhat, Armenian Basketflower, Grossheimia macrocephala


Centaurea macrocephala (Giant Knapweed) is a large, clump-forming perennial boasting large, bright yellow, thistle-like flowers, 3-4 in. wide (7-10 cm), enclosed in shiny, papery brown bracts in early to mid summer, Blooming for 2-3 weeks, the blossoms attract bees, butterflies and other pollinating insects. The bold blossoms appear atop sturdy, stiff stems above the foliage of broadly lance-shaped leaves. Native to the Caucasus, Giant Knapweed self-seeds readily and can become invasive. It can out-compete grasses and other forage species, reducing food sources for wildlife and livestock. It is very difficult to remove once established.

  • Grows up to 3-4 ft. tall (90-120 cm) and 1-2 ft. wide (30-60 cm).
  • Performs best in full sun in dry to medium, well-drained soils.
  • Good choice for beds and borders, coastal gardens, cottage gardens, prairies and meadows. Excellent fresh cut flowers. Good for dried arrangements.
  • No serious pest or disease issues. Keep an eye out for powdery mildew.
  • Deadhead regularly to prolong flowering.
  • Propagate by seed sown in pots in a cold frame in spring or propagate by division in spring or autumn.
  • Centaurea macrocephala is native to the Caucasus, where it grows in mountain meadows.
  • Find where this species is invasive in the United States.

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Requirements

Hardiness 3 – 7
Heat Zones 1 – 7
Climate Zones 2, 2A, 2B, 3, 3A, 3B, 4, 5, 6, 7, 8, 9, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24
Plant Type Perennials
Plant Family Centaurea - Cornflowers
Exposure Full Sun
Season of Interest Summer (Early,Mid)
Height 3' – 4' (90cm – 120cm)
Spread 1' – 2' (30cm – 60cm)
Spacing 16" – 24" (40cm – 60cm)
Water Needs Low, Average
Maintenance Low
Soil Type Chalk, Clay, Loam, Sand
Soil pH Acid, Alkaline, Neutral
Soil Drainage Moist but Well-Drained, Well-Drained
Characteristics Dried Arrangements, Cut Flowers, Showy
Tolerance Drought, Dry Soil
Attracts Birds, Butterflies
Garden Uses Beds and Borders
Garden Styles Coastal Garden, Informal and Cottage, Prairie and Meadow

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Vladimir Vasiltvich, Shutterstock, Chanticleer Garden

While every effort has been made to describe these plants accurately, please keep in mind that height, bloom time, and color may differ in various climates. The description of these plants has been written based on numerous outside resources.


Requirements

Hardiness 3 – 7
Heat Zones 1 – 7
Climate Zones 2, 2A, 2B, 3, 3A, 3B, 4, 5, 6, 7, 8, 9, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24
Plant Type Perennials
Plant Family Centaurea - Cornflowers
Exposure Full Sun
Season of Interest Summer (Early,Mid)
Height 3' – 4' (90cm – 120cm)
Spread 1' – 2' (30cm – 60cm)
Spacing 16" – 24" (40cm – 60cm)
Water Needs Low, Average
Maintenance Low
Soil Type Chalk, Clay, Loam, Sand
Soil pH Acid, Alkaline, Neutral
Soil Drainage Moist but Well-Drained, Well-Drained
Characteristics Dried Arrangements, Cut Flowers, Showy
Tolerance Drought, Dry Soil
Attracts Birds, Butterflies
Garden Uses Beds and Borders
Garden Styles Coastal Garden, Informal and Cottage, Prairie and Meadow

Great Plant Combination Ideas with Centaurea - Cornflowers

Guides with Centaurea - Cornflowers

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