Crown vetch or Coronilla varia is a cool-season hardy perennial legume. It is not a true species of vetch, but resembles the common hairy vetch in appearance. Crown vetch spreads through its rhizomes and forms a dense ground cover. It is used as a soil stabilizer that protects road banks from erosion. It is also used in ornamental plantings. It is being tried out as a livestock forage. It is a nonbloating feed, and the young growth of crown vetch contains crude protein and fiber in similar amounts to other legume hays.
Crown vetch can survive in a wide variety of climates. It grows best in well-drained soils. It will tolerate low pH and low fertility in soils. Lime, phosphorus and potassium fertilizers are the best types to apply to crown vetch. There are three varieties of crown vetch--Emerald, Penngift and Chemung. Chemung and Emerald grow quicker and taller than Penngift. They also have coarser stems and wider leaves. Emerald grows well in the Midwest, and Chemung is adapted to the growing conditions of the Northeast.
Crown vetch seeds need to be inoculated before planting. The required bacteria strain is available where the seeds are obtained. Since the seeds are very small and smooth, it is hard to get the bacteria to stick to them. Adding sugar water to the inoculations makes it stick better to the seeds.
Crown vetch seed should be spread at a rate of 5 to 15 lbs. per acre. Since the seed price is high for crown vetch seeds, it is economical to keep the seeding rate low. To promote successful germination rates, inoculate seeds, use chemical weed control and use special seeding equipment adapted to spread small seeds. Lime, phosphate and potash will stimulate young crown vetch plant growth. Do not use nitrogen, because it will stimulate weed growth, which will smother the newly sprouted crown vetch.
Plow under the seedbed the fall before planting to control weeds. Sow the seeds from March 15 to May 15 in this prepared area. Crown vetch seed can also be sown on a mulch of dead Sudan grass from October to April. Another way is to mix chemical weed control into the soil in the fall. Crown vetch seeds can be sown in rows, and weeds can be tilled under between the rows. Once established, the crown vetch will fill in the rows.
Just a few seedlings will give the results of a good patch of crown vetch. Once seedlings are established, the crown vetch starts to spread through its vigorous rhizome growth. This creeping habit will fill in rows or any gaps between plants. Crown vetch will survive grazing if the soil drainage and fertility is proper. Avoid overgrazing your crown vetch patch, since this will kill it. Just keep 3 to 4 inches of stubble after cutting to keep crown vetch in a productive state of growth.