How Long Does Crown Vetch Spread?
- Crown vetch is a hardy perennial in the pea family. Its leaves consist of 15 to 25 small leaflets, giving them a feathered appearance. The small flowers are white to pink and appear in mid summer. Seed pods are narrow and pointed and appear in crown-like clusters. Creeping underground stems called rhizomes can reach up to 10 feet long. These rhizomes send out above-ground stems that can reach between 2 and 6 feet.
- Since it was used as erosion control at one point, crown vetch is mostly found in ditches and along roadsides. It is listed as naturalized in all but four U.S. states, according to the Invasive Plant Species Assessment Working Group. Crown vetch spreads vegetatively via its underground rhizomes and by seed, making it capable of growing over a large area. It prefers sunny, open areas but can withstand a wide range of conditions including cold, drought and extreme amounts of precipitation.
- Because it grows so quickly, is able to readily reseed and is perennial, crown vetch is capable of continuing its spread for many years. As it spreads it covers trees, shrubs and other native plants, effectively smothering them. In fact, seeds can remain dormant for up to 15 years, increasing the amount of time this plant can be a problem. There is evidence that it uses valuable nitrogen resources, denying them to other plants, according to Invasive Plant Species Assessment Working Group.
- Mowing and burning are somewhat effective methods of controlling crown vetch. Both methods must be completed several times a year over several years to adequately control the plant. Hand removal is possible but impractical as every part of the stem, root and rhizome must be removed and destroyed to prevent re-sprouting. Products containing the chemicals 2,4-D amine, triclopyr, glyphosate and clopyralid can be effective as well. Always follow manufacturer's directions when using herbicides.