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

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

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.