We have found 26 plants that meet your criteria.

Agapanthus africanus African Lily Globes of blue flowers in late summer £6.84 Buy
Agapanthus 'Headbourne hybrids' African Lily Showy globes of blue and white flowers £6.84 Buy
Aquilegia vulgaris var. 'stellata Blue Barlow' Granny's Bonnet Stunning violet-blue double flowers £5.37 Buy
Aster x frikartii 'Mönch' Michaelmas Daisy Lavender-blue, daisy flowers £5.86 Buy
Aster 'Little Carlow (cordifolius hybrid)' Aster Pretty violet-blue daisies in late summer £5.86 Buy
Campanula lactiflora 'Pritchard's Variety' Milky Bellflower Masses of bell-like lilac flowers £5.86 Buy
Geranium 'Spinners' Cranesbill Wonderful large deep purple blue blooms £5.86 Buy
Price Pruned
Iris pallida 'Argenteovariegata' Great Purple Flag Stunning grey-green and white variegated leaves NOW £5.86 Buy
Iris sibirica 'Caesar's Brother' Siberian Iris Intense violet flowers. Great in boggy ground £5.86 Buy
Iris sibirica 'Perry's Blue' Siberian Flag Looks great planted in bold clumps £5.86 Buy
Iris sibirica 'Silver Edge' Siberian Flag Blue flowers edged with white £5.86 Buy
Iris sibirica 'Tropic Night' Siberian Flag Violet flowers with yellow throats. Good for boggy ground £5.86 Buy
Nepeta subsessilis 'Cool Cat' Catmint Lavender-blue flowers. Great for a herb garden £5.86 Buy
Nepeta subsessilis 'Washfield' Catmint Pretty catmint with bright blue flowers £5.86 Buy
Price Pruned
Nepeta 'Six Hills Giant' Catmint A hardy catmint with lavender flowers NOW £4.88 Buy
Price Pruned
Phlox paniculata 'Blue Paradise' Perennial Phlox Fragrant violet flowers all summer NOW £5.37 Buy
Salvia patens Sage Large, stunning blue blooms £5.86 Buy
Price Pruned
Amsonia tabernaemontana Amsonia Dense clusters of ice-blue, star-like flowers NOW £5.86 Buy
Geranium sylvaticum 'Mayflower' Wood Cranesbill Intense violet-blue flowers. Ideal for woodland £5.37 Buy
Hosta sieboldiana var. elegans Plaintain Lily Heart shaped, pale green leaves and fragrant flowers £5.86 Buy