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

Eryngium x zabelii 'Big Blue (Sea Holly 'Big Blue): Large electric-blue thimble-shaped flowers with a spiky collar and silver-green foliage. Long flowering and bee-friendly. Hardy. Up to 75cm [Collect Only]

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.

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.