Hello Naomi

    That certainly does seem like a nice little garden! Now lets see if we can help you with that crown vetch your dealing with. 

           According to both the DNR and Purdue university, the biggest problem we are facing is that crown vetch reproduces both through seed and underground rhizomes. Which can make it a real pain to remove from a garden. Generally we would approach this with the least harmful methods first, in this situation though I believe we should utilize two methods. First I would suggest some physical control. Since we know it spreads rapidly from seed I would suggest you mow or cut it close to but not all the way to the ground and make sure it does not flower and go to seed. You could try digging up all the roots and disposing of them but because of its growth habits it's probably more work than it's worth and you may actually help it spread quicker.

    The next step I would suggest would be like you said, apply some herbicide. I would however apply it to the cut down bits of crown vetch. The method of application varies by the manufacture but you should be able to spray or brush the herbicide onto the crown vetch. Just be very careful not to get any on your other plants. The herbicides I would recommend would be.

     A Clopyralid containing Herbicide, is the most weedy plant selective herbicide in this list.  According to Purdue university "A 0.25% solution of clopyralid with 0.5% surfactant can reportedly kill 100% of crown vetch cover. Or a Triclopyr containing herbicides as it also seems to be %99 percent effective. Glyphosate Is also recommended for spring applications, however from the info I'm finding is not as effective as the previously mentioned herbicides. And remember anytime you use an herbicide or pesticide. Don't forget your personal protective equipment, and Always read the label and follow directions.

       I Hope this helps with your battle against that pesty crown vetch. If you have any questions or concerns. You can reach out to me or the extension. Happy Gardening!!!