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.

Erigeron karvinskianus 'Lavender Lady' (Fleabane 'Lavender Lady'): A lavender flowered form of this delicate but robust daisy. Self-seeds around where happy. To 20cm. Hardy.

Geranium wlassovianum: Warm purple flowers over attractive velvety foliage. Excellent autumn foliage colour.

Lathyrus vernus (Spring pea): Two-tone purple and pink pea-like flowers in early spring. Thrives in shade, even quite dry shade. To 30cm. Hardy.

Liriope 'Big Blue' (Blue turf lily 'Big Blue'): Spikes of vibrant purple flowers in autumn, larger than the usual form, evergreen strappy foliage. Good for dry shade. Hardy. Up to 50cm

Liriope muscari 'Royal Purple' (Blue turf lily 'Royal Purple'): Spikes of deep purple flowers in autumn above dark-green evergreen strappy foliage. Can tolerate dry shade. Hardy. Up to 50cm.

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.