(Greater knapweed). Basal clumps of lobed green leaves and upright stems of ball-shaped buds which burst open to reveal rose-purple cornflowers to 3 inches across, with long, fringed outer petals. A hardy perennial ideal for wildflower gardens or mixed borders and an excellent source of nectar for the bees and butterflies. Full sun and average soil, don’t over-feed. 70-90cm high x 40cm wide. 1 litre pot.