Cardamine raphanifolia aka Greater Cuckooflower

Cardamine raphanifolia is a herbaceous perennial in the cabbage family, Brassicaceae. Its common names include greater cuckoo flower and broad-leaved cuckoo flower. Its native range runs from southern France to northern Spain. It grows in temperate regions, in damp mountain sites and beside streams. It is not native to Britain or Ireland.

This plant forms clumps and spreads through thick underground rhizomes. Garden plants reach about 0.3–1.6 feet [0.1–0.5 metres] tall. Their spread reaches 1.6–3.3 feet [0.5–1 metre]. The RHS lists about one year to reach mature size. Dark green, pinnate leaves form a low, dense cover. The foliage is deciduous, so that cover does not last year-round. Slender stems rise above the leaves in early summer. They bear clusters of lilac-pink or white flowers. Each flower has four petals.

Choose soil with plenty of organic matter that holds moisture. The plant grows in full sun or partial shade. It accepts clay, loam, and chalk soils. Acid, neutral, and alkaline conditions all suit it. Moist soil can drain well or drain poorly. This gives gardeners scope to use it in damp beds. The RHS rates its winter hardiness as H7. This covers the coldest European continental conditions, below minus 20°C. Plants For A Future lists USDA zones 4–8.

Its spreading growth makes it useful as ground cover in moist sites. Plants For A Future suggests woodland gardens and bog gardens. Dappled shade and shaded edges are also suitable settings. The RHS suggests cottage gardens, informal beds, borders, and wildflower meadows. No pruning is needed. Rhizomes and self-sown seed provide ways for plants to spread. Gardeners can divide mature clumps once flowering has ended. Sow collected seed in autumn or spring. Use a cold frame or a sheltered outdoor spot.

Flea beetles and aphids may attack the plant. The RHS reports few disease problems in general. Plants For A Future does not flag it as weedy. Still, its rhizomes and self-seeding matter when choosing a site. That source lists no known medicinal uses or hazards. It suggests the leaves may be edible, but lacks firm information. Treat that as uncertain, not as proof of food safety. The evidence also does not establish safety for pets.