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.

Baptisia australis (Indigo weed): Spires of lipped indigo flowers over olive-green foliage. Flowering height 1.2m. [Collect Only]

Eryngium alpinum 'Blue Star': Large electric-blue flowers with a spiky collar and spiky silver-green foliage. Slightly shorter then some other Eryngium varieties. Hardy. Up to 70cm. [Collect Only]

Eryngium bourgatii 'Picos Amethyst'': Stunning steely blue flowers on stiff stems with a gorgeous purple tint. Loves sunshine and well-drained soil. To 70cm. [Collect Only]

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

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.

Hepatica nobilis: Pretty bowl shaped blue flowers in early spring.

Salvia patens 'Cambridge Blue': Beautiful Salvia with pale blue two-lipped flowers flowering in late summer. Needs a sunny, sheltered position and protect with mulch.To 1m.