This perennial dies back to below ground level each year in autumn, then fresh new growth appears again in spring.

• Position: full sun or partial shade
• Soil: fertile, well-drained soil
• Rate of growth: fast-growing
• Flowering period: June to October
• Hardiness: fully hardy
  
  Winner of the RHS Plant of the Centenary at Chelsea Flower Show in 2013
  
  Each lavender-blue, saucer-shaped flower grows up to 5cm across, and has a white eye with purple veining. A spreading form, it looks wonderful in naturalised planting schemes, where it provides fast-growing ground cover, and will flower from early summer to mid-autumn.
  
  
• Garden care: In midsummer rejuvenate plants that are beginning to look jaded, by removing old flowered stems and leaves. Lift and divide large colonies in spring.