That's very quick. If I put it in my garden, I'd definitely have some type of physical barrier. So, you could plant it in a pot that was bigger or use a metal hoop, maybe eight to ten inches deep. And then, divide it every spring to lessen the size of it. You've actually got some containers that you made for a real common aggressive perennial here.
Mints are great to use in cooking and for other herbal uses, of course.
I love them in teas. I don't love them in my garden anymore, though, because they went under the sidewalk and took off. Well, they're pretty aggressive. And what we've tried to do here to keep them in check, is we built these steel rings. They're about ten inches deep and 8 inches in diameter.