Johnson County Secondary Roads Crown Vetch Weed

Crown Vetch (Coronilla varia)

Description: Crown vetch, a member of the pea family, is perennial, creeping plant with long stems that may reach up to 6-8 feet in length. Each compound leaf has 15-25 leaflets. Crown vetch spreads by seed and its branched, creeping root system. Flowers are pink or white and are usually in clusters at the ends of the stalks.

Distribution: Crown vetch was introduced in the United States from Europe and Africa. It was brought here for erosion control and a green fertilizer crop. Highway departments and erosion control companies used the plant extensively to control soil movement on steep banks and cuts. Crown vetch prefers open sunny areas and is found along roadsides, railroads, and occasionally pastures. It is still sold for household landscaping, even though better choices exist. Crown vetch is found throughout Johnson County and Iowa.

What’s The Problem?: Crown vetch forms a dense mat of suffocating vegetation, which excludes native plants, and can promote erosion. Large crown vetch vegetative mats grow from very few root stems, which do a poor job of holding soil in place. Native plants can be smothered by this beautiful, aggressive species, and habitats that were once valuable for wildlife can be overtaken and turn into worthless weed patches.

Management Methods: There are several methods for control of crown vetch. Mowing can be done in late spring to stress plants and lower seed production. Prescribed burning in late spring will also help control efforts. Careful use of burndown herbicides, applied when the plant is actively growing, will setback the plant. These methods are very effective if used in combination with each other. One of the best ways to manage crown vetch is to discontinue its use as a landscape or garden plant species. While it is a beautiful plant, crown vetch is a deceptively destructive species, ecologically speaking. Better choices, some native species, exist which do not have the negative growth characteristics of crown vetch. Consult with plant and weed professionals or garden centers for ideas on plant alternatives.

Photos courtesy of Charles Peirce
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