Aconitum napellus (Monkshood): Dark blue hooded flowers over finely divided foliage. This Aconitum flowers early, in late spring/early summer. Height to 1.5m. Hardy. [Collect Only]

Agastache rugosa 'Liquorice Blue' (Korean mint 'Liquorice Blue'): Spikes of warm blue lipped flowers from late June onwards. Very attractive to bees. Aromatic foliage. To 1.5m. Hardy in light soils.

Echinops bannaticus 'Taplow Blue' (Globe thistle): Tall stems of pale blue globe flowers, clumps of spiny, grey-green leaves with silver undersides. Bee-friendly. Hardy. Up to 1.5m.

Salvia uliginosa (Bog Sage): Branched stems of clear blue flowers and lance-shaped leaves. Needs a sunny spot but with moist soil. Late flowering. To 2m.