Aster 'Little Carlow' (Syn. Symphyotrichum 'Little Carlow' (cordifolium hybrid)): Large sprays of small purplish blue flowers in autumn. Very reliable, easy to grow perennial. Up to 1m.

Campanula lactiflora 'Prichards Variety' (Milky bellflower 'Prichards Variety'): Clusters of warm blue flowers on tall stems in mid-summer. To 1m. Hardy.

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.