Corydalis are variable perennials - some with tuberous roots or rhizomes - others with fibrous roots.
We only discuss the care and planting of the tuberous and rhizome types in this section. The Corydalis that have tubers are generally summer dormant, in that they die down soon after late spring or early summer flowering and remain dormant throughout late summer and winter.
The tuberous Corydalis generally prefer moist soils, though are happy to habituate soils that are dry in the summer - their dormancy period.
Corydalis flexuosa 'Craighton Blue' has flowers which are typical of the group - all with a long erect spur at top of upturned flowers. The pendulous part of the flower being trumpet or horn shaped and housing the stamens and anthers which are accessed from within by those flying insects that can alight, and enter.
This cultivar in fact has a fibrous root system, which house small bulbils - used as the storage organs for food in the dormancy period.
It prefers semi shaded areas, though will tolerate early or late sun during the day. It does not like crowded conditions, and is far happier isolated - or at least not hassled by other plants. The foliage is as delicate as the flowers, and attractive light green foliage held on bronzed stems.
Seed propagation is possible by sowing the gathered seed as soon a ripe and keeping in cold frame until germinated.