We have found 17 plants that meet your criteria.

Price Pruned
Allium ‘Allium cristophii’ Huge globes of star-like, lilac flowers NOW £5.99 Buy
Angelica ‘Angelica gigas’ Tall, dramatic burgundy flowers £6.99 Buy
Balkan Cranesbill ‘Geranium macrorrhizum Bevan's Variety’ Magenta flowers. Perfect for suppressing weeds £5.99 Buy
Price Pruned
Bergamot ‘Monarda Ou Charm’ Pretty, pink flowers and purple bracts NOW £5.49 Buy
Catmint ‘Nepeta x faassenii Kit Cat’ A dwarf variety with purple flowers £5.99 Buy
Catnip ‘Nepeta racemosa Walker's Low’ Long flowering period £5.99 Buy
Chives ‘Allium schoenoprasum’ Edible leaves and purple, button flowers £3.99 Buy
Giant Catmint ‘Nepeta grandiflora Wild Cat’ A giant catmint with deep purple-blue flowers £5.99 Buy
Hyssop ‘Agastache Black Adder’ Distinctive violet, bottlebrush flowers £5.99 Buy
Perennial Phlox ‘Phlox paniculata Amethyst’ Tall variety with violet flowers £5.99 Buy
Price Pruned
Pink ‘Dianthus amurensis’ A mat-forming pink with mauve flowers NOW £4.99 Buy
Price Pruned
Round-headed Leek ‘Allium sphaerocephalon’ Small, wine-coloured flowers on tall stems NOW £5.49 coming soon
Sage ‘Salvia nemorosa Ostfriesland’ Attractive to butterflies and bees £5.99 Buy
New
Salvia ‘Salvia nemorosa Amethyst’ Lilac-purple spires of flowers £5.99 Buy
Salvia ‘Salvia nemorosa Caradonna’ Dazzling purple blooms £5.99 Buy
Sweet Rocket ‘Hesperis matronalis’ Lilac flowers. Perfect for a wildlife garden £5.49 coming soon
Price Pruned
Sweet Violet ‘Viola odorata’ Sweetly fragrant flowers NOW £4.99 Buy