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.