Liatris spicata 'Kobold' (Gayfeather 'Kobold'): Plump spikes of purple flowers in mid to late summer. Likes dryish soil in a sunny spot. To 80cm. Hardy

Salvia nemorosa 'Amethyst' (Balkan Clary 'Amethyst'): Slender spires of long-lasting warm purple spikes from mid to late summer. To 90cm. Hardy.

Verbena officinalis 'Bampton' (Vervain 'Bampton'): Attractive plant with dark purple foliage and upright, wiry stems with delicate purple flowers. Long flowering. Up to 90cm. Hardy.