I really like it as a nn, either for
Josephine, or for any flower name. If I ended up using
Violet, I'd probably call her
Posy from time to time. It reminds me of the character Bunchy in the Milly-Molly-Mandy books, whose really name was
Violet Rosemary May (I think).
Totally unrelated: just wiki'd
Milly Molly Mandy to check that I'd got the character's name right. Apparently the stories were created for a
Christian Science magazine.