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Mountain knapweed, Perennial cornflower, Cornflower
Centaurea montana (Mountain knapweed). This is an upright spreading perennial, It will bear long-blooming flowers that are purple-blue or pink. The fringed flowers are blue and will stand out against the dark silver green leaves.
They will prefer full sun but do not bloom well if allowed to dry out. You will need to divide these plants every 2 to 3 years to keep them growing vigorously.
Border, naturaliser, cutting bed, rock-garden. Spring/summer interest.