Acanthus hungaricus (Long-leaved bear's breeches): Architectural spires of purple/white flowers over large, dark green deeply divided leaves. Best in sun or light shade. Height to 1.2m [Collect Only]

Centaurea 'Jordy' (Perennial cornflower 'Jordy'): Beautiful maroon-purple flowers over felty silvery-green foliage.

Centaurea montana 'Parham' (Perennial cornflower 'Parham'): Large lavender purple fluffy flowers over silvery-green foliage. To 40cm. Hardy

Cynara cardunculus (Cardoon): Dramatic, tall silver leaved plant topped with large purple thistle flowers in mid-summer. Hardy. Up to 2.5m.

Penstemon 'Sour Grapes' (Syn. Stapleford Gem): Purple-blue tubular flowers with a metallic sheen and patches of white in the throat. Protect from hard frosts. To 60cm.

Perovskia 'Blue Spire' (Russian Sage 'Blue Spire'): Fine spikes of purple flowers on silver stems. Lovely winter stem effect. Hardy. Up to 1m.

Verbena bonariensis: Tall, airy but strong slender stems with flat heads of purple flowers in mid to late summer. To 1.8m. Frost-hardy.