Corydalis flexuosa 'Pierre David'

Fumitory Fumariaceae

A blue Corydalis that apparently believes blue is a perfectly adequate colour for an entire career. This refined selection of the Chinese Corydalis flexuosa produces finely divided, glaucous-green foliage topped by clusters of wonderfully rich, gentian-blue flowers, often continuing for an unusually long period when conditions suit it. It is a particularly elegant plant for the woodland garden, where its cool colouring works beautifully among ferns, hostas and other shade-loving perennials.

Like many forms of C. flexuosa, it appreciates fertile, humus-rich soil that remains reasonably moist but well drained, preferably in partial shade. It may retreat into summer dormancy during hot or dry conditions — less a disappearance than a sensible refusal to work through the holidays. Give it cool roots and decent moisture and it will return reliably each spring, bringing some of the best blue flowers available for shade.

Flowering: April–June, sometimes later
Hardiness: H5, approximately –15 to –10°C
Height: 30–40cm
Spread: 30–45cm
Origin: Selected form of Corydalis flexuosa, China