Amsonia tabernaemontana (Blue dogbane): Starry blue flowers on strong stems with willowy green leaves. Hardy. Up to 90cm. [Collect Only]

Campanula lactiflora 'Prichards Variety' (Milky bellflower 'Prichards Variety'): Clusters of warm blue flowers on tall stems in mid-summer. To 1.5m. Hardy. [Collect Only]

Campanula persicifolia (Peach-leaved bellflower): Tall spikes of large, cup-shaped blue flowers over slender foliage in mid-summer. To 1.2m. Hardy

Catananche caerulea (Cupid's dart): Masses of papery lavender blue flowers held on wiry stems all summer. Seed heads turn silver in late summer. Good dried flower. Up to 60cm.

Catananche caerulea 'Major' (Cupid's dart 'Major'): Masses of papery blue flowers held on wiry stems all summer. Seed heads turn silver in late summer.

Echinops bannaticus 'Blue Globe' (Globe thistle): Tall upright stems of bright blue globe flowers above clumps of spiny, grey-green leaves. Bee-friendly. Hardy. Up to 1.2m.

Echinops ritro (Globe Thistle): Blue globes held above stout grey green foliage. Attractive to bees. Likes well drained soil and plenty of sun. Hardy. Up to 1m.

Echinops ritro 'Veitch's Blue' (Globe thistle): Dark blue spherical flower heads above attractive grey-green foliage. Loved by bees and butterflies. Hardy. Up to 1m [Collect Only]

Eryngium bourgatii Graham Stuart Thomas's selection (Sea Holly Graham Stuart Thomas's selection): Spiny, violet blue flowers in summer of even spinier blue-green leaves with white mid-ribs.

Eryngium planum 'Blue Hobbit' (Sea Holly 'Blue Hobbit'): A more compact form with steely blue flowers on dark stems. Spiny glaucous foliage. Loves sunshine and very well-drained gritty soil. Hardy. Up to 30cm.

Eryngium x zabelii 'Jos Eijking' (Sea Holly 'Jos Eijking'): Large steely blue bracts surround a dome of tiny blue flowers in summer. Long-lasting flowers.Thrives in a sunny,dry spot. To 70cm. Hardy. [Collect Only]

Eryngium x zabelii 'Violetta' (Sea Holly 'Violetta'): Deep dark-blue form of the Sea Holly with bracts surrounding a dome of tiny blue flowers. Thrives in sunny, dry gardens. Hardy. Up to 80cm.

Geranium 'Blue Cloud' (Cranesbill 'Blue Cloud'): Tall cultivar with pale blue flowers & dark purple veining above deeply divided green leaves. Long-flowering. Hardy. Up to 90cm. [Collect Only]

Geranium 'Nimbus' (Cranesbill 'Nimbus'): Makes medium sized domes of finely divided foliage smothered in purplish blue flowers in early summer. To 50cm. Hardy

Geranium pratense 'Cloud Nine' (Meadow cranesbill 'Cloud Nine'): An attractive double form of the familiar meadow cranesbill with lovely soft blue flowers. Strong growing. Hardy. Up to 90cm. [Collect Only]

Geranium pratense 'Mrs Kendall Clark' (Meadow cranesbill 'Mrs Kendall Clark'): Palest purpley/grey flowers, makes a good mound of foliage. Hardy. To 40cm. [Collect Only]

Iris sibirica (Siberian Iris): Soft, purplish blue iris flowers over strappy green foliage. [Collect Only]

Iris sibirica 'Silver Edge' (Siberian Iris 'Silver Edge'): Rich purple flowers with a fine silver picotee petal edge. [Collect Only]

Limonium platyphyllum (Broad leaved Statice): A froth of tiny lavender blue flowers on stiff stems in mid-summer. Likes a dry sunny spot. To 60cm.

Scabiosa caucasica 'Clive Greaves' (Scabious 'Clive Greaves'): A very good reliable old variety of scabious with large blue frilled flowers over lance-shaped grey-green foliage. Height to 60cm. Hardy.

Stokesia laevis 'Blue Star' (Stoke's aster 'Blue Star'): Large fluffy blue flowers in mid-summer, slender green leaves. To 40cm. Hardy

Stokesia laevis 'Purple Parasols' (Stoke's aster 'Purple Parasols'): Large, fluffy purple flowers over slender grey-green foliage. A lovely plant for sunny, well-drained borders. To 40cm. Hardy.