I am convinced that they will grow anywhere, since they do at my house. I have a small crack in the cement stairs leading up to the porch, and I have to pull them out of that crack several times a year. There can't even be much dirt at all in there because the crack is so small! I'm surprised that the seeds are able to get in there, but they do. I've also had them come up in the middle of the street, and it's paved! Any little crack with a tiny bit of dirt seems to be enough for them. It's a good thing that they are pretty, because I'd be screaming at them if they weren't!
