Corydalis flexuosa was a great introduction in the 1990s, and it has also given rise to several excellent hybrids. They are all plants with delicate foliage growing through the winter, after a dormant season in late summer. Then in spring the stems are topped with the distinctive blue flowers, over a long flowering period. Each will soon form a good patch, which can be split to provide a lovely ground cover between shrubs.

Corydalis 'Craigton Blue' is a fine hybrid, which looks great even when now in flower, with its red stems standing upright about bright green, deeply divided foliage. The flowers come in clusters of many individuals, each flower having parts that are every shade from white to deep blue. From a distance it looks sky blue, but definitely repays closer attention. Its main flowering season is late spring, but it just goes on and on producing more.