Calamintha nepeta 'Blue Cloud':
Spikes of small, soft blue flowers above mounds of minty scented green leaves. Loved by bees and butterflies. Hardy. Up to 30cm.
Corydalis elata:
Summer flowering Corydalis with bright blue flowers above soft green foliage. Excellent in some shade in moist soil. Hardy. Up to 30cm.
Phlox divaricata 'Clouds of Perfume':
Deliciously scented and delicate pale blue flowers which are long-lasting. Prefers some partial shade. Hardy. Up to 30cm.