Crown Vetch

(Fabaceae [also known as Leguminosae] - Pea Family)

Form

• herbaceous viney perennial groundcover
• mounding to 2' tall and spreading several feet in diameter during the growing season, but dying back to the crown by December
• mounding mat to procumbent mat growth habit

Culture

• full sun to partial sun
• prefers moist to dry, deep, average, well-drained soils in full sun, and is very urban tolerant, especially in poor, rocky, well-drained, dry soils under hot and humid conditions (it has a deep taproot to obtain Summer moisture, but must have adequate drainage to avoid crown rot and root rot)
• propagated by crown division, rooted stem cuttings, and seeds
• Pea Family, with crown rot and root rot under poor drainage conditions being the primary disease problem
• low availability, in containers or flats
• site individual plants close enough together to have dense groundcover coverage by the second year after planting (e.g., 2' apart in staggered rows with mulch) to avoid vertical-growing weeds from invading the site, or apply appropriate herbicides (note that this plant is a member of the Pea Family [Fabaceae or Leguminosae])

Foliage

• dark green, alternate leaves are pinnately compound and fine-textured, to 1' long, with 11 to 25 small leaflets per leaf

Flowers

• inflorescences are mauve to lavender-pink-white, resembling clover, with each entire inflorescence only 1" across but numerously arranged along the stems and quite attractive, arising on long pedicels from the leaf axils above the dense green foliage in June and July and sporadically thereafter
• mildly fragrant, especially in a mass planting, and attracting many bees

Fruits

• ornamentally inconspicuous

Twigs

• several long, relatively unbranched green stems arise from each crown and radiate to cover several square feet of surrounding area with dense foliage
• stems die back to the crown in late Autumn

Trunk

• not applicable

ID Summary

• pinnately compound foliage alternates along the long, prostrate to mounding vine-like stems that cover embankments or flat barren areas, flowering profusely in mid-Summer with white-pink, clover-like, mildly fragrant inflorescences, but with the stems dying back to the crowns by late Autumn

USAGE

Function

• erosion control and vegetative coverage as a rambling viney groundcover for embankments, slopes, ravines, and neglected areas, and also cascading and tumbling over walls and rockery

Texture

• fine texture
• thick density (if it is planted densely enough for complete groundcover coverage)

Assets

• rapid establishment, with both deep taproots and sprawling vegetative coverage for erosion control in sunny areas
• fine-textured dark green foliage
• mildly fragrant and subtlely attractive Summer inflorescences

Liabilities

• vertical weeds can easily push through gaps in the procumbent stems if the groundcover is not planted densely enough, or if mulch or appropriate herbicides are not applied to the soil around the plants
• tends to die out with age, often from crown rot or root rot in poorly drained soils
• can become overly aggressive under optimum growth conditions, especially if sited adjacent to other desirable plants (such as perennials)
• large areas covered with a solid mass planting will become barren in Winter, as this groundcover dies back to the crown each Autumn

Habitat

• zones 3 to 9
• native to Europe, but naturalized in Eastern North America

SELECTIONS

Alternates

• groundcovers with dense foliage for sunny areas (Euonymus fortunei 'Colorata', Hedera helix)
• Summer-flowering groundcovers (Hypericum calycinum, Sedum spurium)

Variants

• Coronilla varia 'Emerald' and 'Penngift' - the two standard cultivars in the nursery trade.

NOTES

Translation

• Coronilla translates as "small crown", referring to the circular arrangement of the individual flowers in the inflorescence.
• varia translates as "variable", perhaps referring to the fact that most species in this genus are shrubs.

Purpose

• Crown Vetch is a Summer-flowering ornamental groundcover that is often used for erosion control on steep embankments that would be difficult to mow, or in neglected variable-terrain areas with poor but well-drained soil.

Summary

• Coronilla varia is a vigorous deciduous groundcover, densely mounding and dark-green foliaged, often found covering sunny embankments and slopes in an erosion control situation, with ornamental Summer pink-white inflorescences.