We have found 20 plants that meet your criteria.

Price Pruned
Dalmatian Bellflower ‘Campanula portenschlagiana’ Vigorous and low-growing NOW £4.99 Buy
Price Pruned
Pink ‘Dianthus amurensis’ A mat-forming pink with mauve flowers NOW £4.99 Buy
Balkan Cranesbill ‘Geranium macrorrhizum Bevan's Variety’ Magenta flowers. Perfect for suppressing weeds £5.99 Buy
Stinking Gladwyn ‘Iris foetidissima’ Bright orange berries. Useful for dry shade £5.99 Buy
Price Pruned
Big Blue Lily-turf ‘Liriope muscari’ Purple, wand-like flowers and evergreen foliage NOW £5.99 Buy
Catnip ‘Nepeta racemosa Walker's Low’ Long flowering period £5.99 Buy
Catmint ‘Nepeta x faassenii Kit Cat’ A dwarf variety with purple flowers £5.99 Buy
Jerusalem Sage ‘Phlomis tuberosa Amazone’ Whorls of lilac flowers and architectural seedheads £6.99 Buy
Lamb's Ears ‘Stachys byzantina Big Ears’ Purple flowers large Grey-green leaves £5.49 Buy
Germander ‘Teucrium hircanicum Paradise Delight’ Great tail-like flowers £5.99 Buy
Tower of Jewels ‘Echium pininana’ Enormous spikes of blue flowers £6.99 Buy
Wallflower ‘Erysimum Bowles' Mauve’ Stunning mauve flowers £5.99 Buy
Giant Catmint ‘Nepeta grandiflora Wild Cat’ A giant catmint with deep purple-blue flowers £5.99 Buy
Purple Mullein ‘Verbascum phoeniceum Violetta’ Spires of papery purple blooms £6.99 Buy
Lesser Periwinkle ‘Vinca minor Atropurpurea’ Delicious dark damson-purple flowers £5.99 Buy
Price Pruned
Sweet Violet ‘Viola odorata’ Sweetly fragrant flowers NOW £4.99 Buy
Wood Violet (syn. Viola labradonica... ‘Viola riviniana Purpurea Group’ Ideal for a woodland garden £4.99 Buy
Angel's fishing rod ‘Dierama Purple Passion’ Dark, delicate bell shaped flowers £7.99 coming soon
Pride of Madeira ‘Echium candicans’ Dramatic purple spikes in early summer. Drought tolerant £5.99 coming soon
Price Pruned
Phlox ‘Phlox divaricata subsp. laphamii Chattahoochee’ Masses of lilac flowers. Perfect in partial shade NOW £5.49 coming soon