Crocus nudiflorus aka Knights Of St John Crocus

Crocus nudiflorus is a small plant that blooms in autumn. It belongs to the iris family, Iridaceae. Common names include autumnal crocus and naked-flowered crocus. It comes from France and Spain, where it grows in meadows. It is not native to Britain or Ireland. This perennial lives for years and sheds its leaves. It grows from a corm beneath the soil. Its blooms come before its leaves, hence the naked-flowered name.

Plants reach about 0.33 feet [0.1 metres] tall and wide. Their small, upright form suits low plantings. Each corm tends to bear one flower in autumn. The bloom has a long tube and purple petals. These range from deep purple to lilac-purple. The throat has a lighter shade. A bright orange or yellow stigma adds contrast. Narrow, linear leaves grow from the base in winter and spring. These leaves come after the blooms, not with them.

The RHS advises moist soil rich in humus and partial shade. Its guide also lists full sun as a good choice. Soil must drain well, even when it stays moist. The listed soils include chalk, clay, loam and sand. It copes with acid, neutral and alkaline soil. The RHS rates its hardiness as H6. This means minimum temperatures of about −20 to −15°C. Plants For A Future lists USDA zones 4–8. The RHS says plants reach full size in two to five years.

This crocus suits grass where it can spread and settle. Suggested sites include wildflower meadows and wildlife gardens. Patios and containers are other choices. Plants For A Future also lists lawns and beds. It includes woodland with patches of light and shade. Small size and autumn blooms suit these low plantings. The RHS lists it for gardens that need little care. It needs no pruning. Sow ripe seed in containers in a cold frame. Or split off cormlets, the small new corms, while plants rest.

The RHS reports few disease problems, but stored corms can rot. Birds and rodents may cause harm too. It warns that people and pets must not eat these ornamental corms. Wear gloves and protective gear when you handle them. Plants For A Future records use as a saffron substitute. But its detailed notes on food and medicine concern another species. Those notes do not show safe uses for this crocus. Keep the RHS warning in mind when choosing its site.