Q: Can you identify this hideous weed that has invaded my garden? Any help that you can provide to identify it and eliminate this evil scourge would be very helpful.
A: It’s purple vetch, Vicia americana. This legume has been used as a forage for cattle. It also was once an ingredient in lawn seed mixes because it grabs nitrogen from the air and converts it to plant food.
Due to its twining nature, this plant can be a real nuisance in the garden. But my definition of a “weed” is a “plant that makes me unhappy” …..so vetch is a weed for me but might not be for others.
Nothing eradicates vetch permanently. You’ll have to deal with it occasionally if there are any uncontrolled patches near your landscape. Best management is to fight it on three fronts:
- always apply in September a weed preventer that lists broadleaf weeds on the label
- carefully spot spray any new tendrils with organic herbicides (click for sources) when small or with glyphosate (click for sources) at any time.
- hand pull and destroy any vines you discover that have the vetch “bean pods” hanging from them.
If it is snaking among and over your ornamentals, hand pull it now and make a note to control it when it is small next April.
Since there are likely seeds in the ground that will sprout in the next year or two, getting reasonable control usually takes three years.
see Common Vetch