Crown vetch has large showy flower clusters that range in color from very light to very dark pink.
By late summer the crown vetch flowers are maturing into slender seed pods.
Crown vetch is a sprawling herbaceous perennial that creeps and spreads along the ground, blanketing anything in its way with feathery compound leaves carried on thin wiry stems. Beneath the ground, crown vetch is spreading by underground stems (rhizomes), and sending up still more plants as it tries to cover the world. The leaves are about 1 ft (0.3 m) long with 5-12 pairs of oblong leaflets, each about 1 in (2.5 cm) long. Individual plants hold themselves up only a foot or so, but they grow all season and can wind up covering an area of 15 sq ft (1.4 sq m) or more. White, pink or purple cloverlike flower heads are produced throughout the summer and autumn. A dozen or more flowers, each about 0.5 in (1.3 cm) long, are packed into each crown-shaped umbel. The segmented seed pods are slender, 2-4 in (5.1-10.2 cm) long, and contain 3-12 flattened seeds. Crown vetch dies to the ground in winter but its long taproot resprouts quickly in spring. 'Emerald' is a vigorous, low growing ground cover with stems up to 6 ft (1.8 m) long and pale pink flowers. 'Penngift' is a tidier plant that stands about 2 ft (0.6 m) tall and has darker pink flowers.
Crown vetch is native to central and southern Europe. It is widely cultivated as a ground cover and for erosion control in temperate areas of the world, and has become naturalized in much of the U.S. and southern Canada, in some areas totally dominating pastures and abandoned fields.
Culture Light: Full sun. Moisture: Crown vetch thrives with regular watering and hangs on during droughts. Hardiness: USDA Zones 4 - 9. Propagation: Crown vetch is grown from seed which usually germinates quickly. Seed should be inoculated with the appropriate legume bacteria. Crown vetch seed can be sown right into grassy or weedy areas without soil preparation.
This planting of crown vetch is controlling erosion along a Kentucky highway (where it is also listed by that state's Exotic Pest Plant Council List as posing a "severe threat").
Crown vetch is weedy and aggressive, and not really suited to gardens. It is valuable for quickly covering slopes and controlling erosion before other, more permanent, plants become established. Crown vetch is an excellent soil binder. Use it to cover dry, rocky slopes. It is used commonly on sloping highway shoulders.
Crown vetch is a legume which gets its nitrogen directly from the air with the help of symbiotic bacteria that live in association with its roots. Thus it does not require nitrogen fertilizer. Learn more about nitrogen fixing in legumes in the Floridata profile for garden peas (Pisum sativum).
Crown vetch can be invasive under favorable conditions. The Tennessee Exotic Pest Plant Council and similar organizations in many other states list crown vetch as a "significant threat" to native plant communities. It is listed as an invasive plant in Ontario, Canada as well. Crown vetch may smother out desirable perennials in its path.