We have found 10 plants that meet your criteria.

Dusky Cranesbill ‘Geranium phaeum’ Small, deep maroon flowers. Good for groundcover £5.99 Buy
Price Pruned
Dusky Cranesbill ‘Geranium phaeum var. phaeum Samobor’ Small, purple-black flowers. Good for damp or dry shade NOW £5.49 Buy
Price Pruned
Big Blue Lily-turf ‘Liriope muscari’ Purple, wand-like flowers and evergreen foliage NOW £5.99 Buy
Price Pruned
Dusky Cranesbill ‘Geranium phaeum Lily Lovell’ Iridescent saucers of purple flowers. Good for shade NOW £5.49 Buy
Lenten Rose ‘Helleborus x hybridus Harvington Shades of Night’ Early spring flowers in shades of deep purple £9.99 Buy
Harvington Hellebore ‘Helleborus x hybridus Smokey Blue’ Unusual, dark purple flowers with a deep blue sheen £9.99 Buy
Stinking Gladwyn ‘Iris foetidissima’ Bright orange berries. Useful for dry shade £5.99 Buy
Lesser Periwinkle ‘Vinca minor Atropurpurea’ Delicious dark damson-purple flowers £5.99 Buy
Balkan Cranesbill ‘Geranium macrorrhizum Bevan's Variety’ Magenta flowers. Perfect for suppressing weeds £5.99 coming soon
Price Pruned
Harvington Hellebore Double ‘Helleborus x hybridus Harvington Smokey Double’ An absolute double stunner! NOW £10.99 coming soon