We had it as a weed around my house since I was little. As far as weeds go, I've dealt with worse. I think it primarily spread by seed (which it probably produces a lot of, judging from the number of tiny flowers), I never noticed it appear to spread via roots or rhizomes.

I'm not sure if it's annual or perennial. You may be able to deadhead the flowers off and avoid reseeding.

Invasiveness in my heavy-clay, Western NY State location is about a 0. I actually have trouble keeping it going - I think the plant I did have is gone. RIP. Not sure I'll keep trying. I think I've killed 4 different plants here over the last 10 years.

FataMorgana

Humm....polar opposite answers there, lol. Maybe I'll give it a go and simply hack off the flower heads before they set seed.
CMK

It doesn't grow all that fast. Ify ou hrvest it to dry and use, I doubt it would be a problem.

It has reseeded in my area, in a spot with little sun but sharp drainage, but was easily overshadowed by other plants eventually.

On the other hand, some I had out next to the street in a pot has overwintered with no protection.

Yes, "invasiveness" and success is largely dependent upon your conditions and so vary wildly. I wish you luck!

FataMorgana

Just to clarify, it was weedy here, but only in areas that you didn't tend to. If you ripped it up before it went to seed it would vanish. I didn't consider it invasive.

Pollinators love it :)