Tufted vetch or cow vetch (Vicia cracca) is an invasive climbing plant from 1 to 6 feet (30-200 cm) high that often becomes a noxious weed in gardens. It produces a thin, wandering stem and pinnate leaves with 8-12 pairs of narrow leaflets. The leaves are tipped in tendrils that the plant uses to climb onto neighboring plants.
Its purple pea-flowerlike blooms appear over a long season, from June to September. They are borne on a thin spike with all the flowers facing the same direction. Afterwards it produces pods much like those of beans or peas, although much smaller, which is not unexpected since tufted vetch belongs to the same family, the pea or legume family (Fabiaceae).
A native of the Old World, tufted vetch was introduced into North America as a forage plant, but is rarely used as such these days. Instead, it long ago escaped from cultivation and now invades gardens, meadows and forest edges throughout the cooler parts of continent, most especially in the Northeast. Once established, it spreads rapidly by seed and underground rhizomes.
Getting Rid of Vetch
Farmers control tufted vetch with repeated herbicide treatments, but in a home garden, that isn’t necessary, because the plant has a weakness you can easily take advantage of.
You see, the tip of each rhizome produces only one stem per year. So if you gently pull on the stem so that it breaks off at its base, or if you cut it off at the base, no new growth will appear that season. And if you pull or cut the plant out early enough in the season, either before it starts to bloom or just at the beginning of flowering season, before the plant has had time to store away reserves for the following year, the rhizome will die of exhaustion and there will be no regrowth the following year.
Try it and see. Just yanking off the top of the plant one year or cutting it to the ground will result in a dramatic drop in numbers the second year: just the plants you missed the first time will sprout. Repeat this a second year to get the stragglers and you’ve pretty much solved the problem. Still, you do have to be careful: there may still be some seeds lying about (they are viable for up to 5 years) and they may occasionally sprout. If you see any vetch seedlings, therefore, pull them out or cut them back too… but they are rarely very numerous.
What to Do With Your Harvest
If the vetches you pulled or cut were not yet producing seeds, you can put their stems, leaves, and flowers in the compost, as they, like most legumes, are very rich in nitrogen. Or just drop them on the ground at the base of your garden plants (no, they will not take root) to enrich the soil. In fact, you could theoretically used tufted vetch as a green manure (there are other faster germinating and easier-to-control legumes for that purpose, though).
If the plants are bearing seed pods, even immature ones, it’s best to not to compost them or use them in any way in the garden: just put them out with the garbage. Even when composted, vetch seeds sometimes survive to restart a new infestation.
Letting Nature Take It Course
Where tufted vetch is not causing you any direct problems (if it grows in a field or a corner you’ve reserved for wildlife, for example), why not simply let it grow? After all, it feeds butterflies, bees and birds and even humans can eat its seeds (some people have a hard time digesting them, though).
Live and let live: always a good motto for a laidback gardener!