Jul 01 2010

Pink Invader

Published by at 7:45 am under Plants

One of the prettiest flowers you’ll see by the road at this time of year is one of the most aggressive, invasive plants in North America.

Crown vetch (Securigera varia) was introduced in the U.S. in the 1950’s during our interstate highway boom.  It was hailed at the time as a fast growing, drought resistant ground cover and planted extensively along the new highways to eliminate the need to mow.

Those same characteristics allowed it to smother the native plants it encountered in its path.

Crown vetch is native to Europe, southwest Asia and northern Africa.  It thrives in open, sunny places, spreading by seed and rhizomes.  It has no North American enemies, nor can it be eaten by farm animals or wildlife because it contains nitroglycosides which cause slow growth and paralysis if consumed in large amounts.

Sixty years after its introduction to America, crown vetch is listed as invasive in 45 states.  If you’ve ever tried to eradicate it you’ll know why.

I once planted a free seed packet of wildflowers in my front garden.  To my dismay the seed company included two — just two! — crown vetch seeds in the mix.  I let them grow that first year.

The next spring I was left with two perennials and two crown vetch plants.  I pulled the vetch and planted new flowers but the vetch reappeared in more places than I’d pulled up.  I weeded, it reappeared, over and over and over again. Yikes!

The only solution was to give up on the other flowers and aggressively pull out every crown vetch plant and its root as soon as it appeared.  It took two years of meticulous weeding before I eradicated the vetch from my small garden.

Sadly, the seed companies still sell crown vetch.

You can buy this pink invader … but DON’T!


(photo by Trisha M. Shears via Wikimedia Commons.  Click on the photo to see the original.)

10 responses so far

10 Responses to “Pink Invader”

  1. Jennieon 01 Jul 2010 at 9:45 am

    Twenty years ago we had a small, sloping back yard. An ad in a newspaper supplement promoted something called “Grandmother’s Flowering Quilt,” along with a closeup of a lovely blossom like the one shown above. It was described as a fast-growing, beautiful ground cover. In my naivete, I did not research it further before sending in my order.

    In the first season alone, it took over not only the slope where I had planted it, but everywhere else as well. It grows quickly in all directions, including up! It was “knee high by the fourth of July,” and was nearly impossible to get rid of. While driving on a local highway, I recognized the “flowering quilt” growing on the hillsides, and later discovered its true name is crown vetch. Just as you discovered, the only way to get rid of it, short of flamethrowers and toxic chemicals, is to yank it out. To get the roots, you have to pretty much dig up the entire area. This episode taught me a valuable lesson: be careful about what you plant 🙁

  2. Kathyon 01 Jul 2010 at 11:18 am

    Well this absolutely convince me that I can’t grow a thing, because years ago, when I lived in Ontario NY, I bought it by name from a catalog and planted it on my sloping hill. I got one tiny cluster of those pretty pink flowers and next year nothing. I guess I was really lucky! Last year while visiting, I drove by the old place and there was nothing but grass on the hill.

  3. faith cornellon 01 Jul 2010 at 11:34 am

    Amazing 2 different stories about crown vetch. The first home I owned was one we had built for us on a lot almost entirely of clay built over the the old clay mines in Beaver County. The soil had to be built up with alot of work but the banks were solid like adobe brick. Bought crown vetch from a nursery (this was in the 60s) & was told it would grow anywhere. Did not grow on the clay banks, eventually just had to cover them with rocks. Guess I had a blessing in disguise also. We eventually had a grassy lawn but it was forever having to add top soil to it so we could grow anything.

  4. Mary Ann Pikeon 01 Jul 2010 at 11:54 am

    And, it’s my understanding that we have Penn State to thank for the proliferation of this invasive. Apparently they developed a strain called Penngift, convinced PennDot to use it on the highways, and with the highway boom in the 50’s and 60’s it spread across the country. I found this article that talks about it:

    The township park next to our house uses crown vetch to cover the hillsides so that they don’t have to maintain them…I’m constantly pulling plants out of my flower beds.

  5. Sharonon 01 Jul 2010 at 5:40 pm

    I’ve also seen it in yellow …. not as wide spread but I have seen it … anyone else?

  6. Kate St. Johnon 01 Jul 2010 at 5:44 pm

    I believe the yellow flowers are a different species of pea (crown vetch is in the pea family). There are also purple pea flowers that are recommended for ground cover now because they have many of the pleasing characteristics of crown vetch EXCEPT they’re native and non-invasive. I am not a plant expert though, so maybe someone else can fill us in on these other varieties of peas that may or may not be better choices than CV.

  7. Marianneon 01 Jul 2010 at 7:30 pm

    I think that the plant Sharon is referring to is Birdsfoot Trefoil, which is in the pea family.

    Here are pics and a short article from Minnesota DNR: http://www.dnr.state.mn.us/invasives/terrestrialplants/herbaceous/birdsfoottrefoil.html

    Here is a more detailed article, from the Penn State College of Agricultural Sciences: http://pubs.cas.psu.edu/FreePubs/pdfs/uc087.pdf

    We also have a problem on our property with crown vetch in our horse pastures. It had been planted here before we bought the property. It spreads ridiculously fast is difficult to control.

  8. Sharonon 02 Jul 2010 at 4:30 am

    Yep … that’s it … thanks!!! *goes back to watching for falcons*

  9. Kate St. Johnon 11 Jul 2016 at 7:04 am

    Nowadays Penn State Extension tells us how to get rid of crown vetch (http://extension.psu.edu/plants/gardening/gardening-questions/spring/how-can-i-get-rid-of-crown-vetch) ending with the statement, “If crown vetch grows near you, it may always be something you need to stay on top of.”

  10. Victoriaon 15 Jul 2016 at 6:04 am

    This grows all across the back lots of our neighborhood. It’s thick tangles are difficult to pull. Each year I battle it in our space, but it surrounds us on either side. I didn’t know what it was. Thank you for this post!

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