This is one of the big projects (for me) that I'm working on right now. My goal is to get rid of the millepertuis (St. John's wort) that is spreading along the south-facing wall of our house. Walt is spraying it every few days with what we are calling "the recipe" — a mixture of highly acidic vinegar (vinaigre ménager), salt, and dishwashing liquid. The spraying seems to be working, as you can see in the photo on the right below. The photo on the left below shows what the millepertuis looked like in June 2015. Here's a link to some posts I've published about millepertuis over the years.
I went out a few days ago and bought a new hedge clipper, because the old one we had was too rusty and dull to cut the millepertuis plants' woody stems. The new clipper cuts better than the old one, but it's still not easy to use. Walt tried to dig up some of the plants using a shovel, but the ground that it's growing in is as hard as concrete. Then I decided that maybe I can let heat kill the plants by covering them with a black plastic tarp and letting the sun do the job. We are expecting a heat wave over the next few days, and that might help. The tarp is three meters wide and 15 meters long. I have a lot of big rocks, bricks, and cinderblocks we can use to hold it down and keep it from blowing away if the weather turns windy.