Q.BAD Idea To Teach People To Plant Crown Vetch?
k3Hi! Just saw your site when googling “Control Crown Vetch,” and (sorry, but..) I was HORRIFIED to see that you were actually teaching people to plant it! Crown vetch is an incredibly destructive invasive species that degrades and destroys native plants and ecosystems, climbs over and smothers native (or garden) plants and shrubs, can disrupt the soil chemistry, and is nearly impossible to eradicate once established. It’s on Ohio’s lists of invasive species, and should NEVER be planted. Especially since if readers from other states are visiting your site, they can be significantly adding to their own states’invasives problems. But … perhaps here’s a better “testimonial” for your gardeners! (P.S. Just to reassure you, I was a gardener at the NY Botanical Garden for almost 10 years, and also worked for The Nature Conservancy, also for 10 years — doing a great deal of invasive-species control) Anyway, your readers should take a gander at this lady’s problem. “Many years ago I was told by a landscaper to plant crown vetch on a steep bank in front of my house. After a few years I realized that this was BAD advice. A couple of years later I called into a national radio garden show to find out how to get rid of the crown vetch … I then asked how long I should wait to plant something else in its place and was told that once the crown vetch was dried up and dead that it was history. Another bit of BAD advice! I went ahead and planted vinca/periwinkle – which I absolutely love. BUT, of course, the crownvetch still grows, like crazy. I usually spend a whole weekend, once the crown vetch has completely towered over the vinca (and blocks my view when I try to back out of my driveway) to pull the invincible weed out so that the vinca “looks” like it’s the only thing growing. Is there anything that I can use to kill the crown vetch, without killing the vinca?

Certified GKH Gardening Expert
You may want to get rid of the vinca, too, because it is also considered invasive and chokes out native plants. If you want to keep it, there is nothing that will kill vetch and not vinca unless you want to do the painstaking job of "painting" an herbicide onto the vetch so you can avoid the vinca.
https://www.gardeningknowhow.com/ornamental/groundcover/periwinkle/vinca-vine-alternatives.htm
https://www.gardeningknowhow.com/ornamental/groundcover/periwinkle/periwinkle-control-methods.htm
This article does say that crown vetch can become invasive:
https://www.gardeningknowhow.com/ornamental/groundcover/crown-vetch/growing-crown-vetch.htm