I'll admit that I wasn't really into
Petunia, until I learned that it means "tobacco". That gave it a whole new dimension for me. So now it interests me a lot! I think the nickname "Tunie" would be very cute (although it might be extra strange in Canada, because we call our two dollar coins "toonies").
I like
Petunia paired with "tough guy" kinda names, something with an edge (Of course, this is my idea of tough guy, YMMV).
Petunia MaxinePetunia Louise Petunia RoxannePetunia MaureenPetunia DenisePetunia MargotPetunia Francine Petunia CharmainePetunia ChantalPetunia Christine (like the killer car)