I've had great results wintersowing petunias. They sprout pretty early (low temps) and tolerate a light to moderate frost just fine. I've had them start blooming in June. As Joanne mentioned, some are daylight sensitive.
Laura Bush are the toughest I've ever seen. And they reseed a lot!!! If you wintersow them once they'll probably come back forever. Last year the LB volunteers kept eating my echinacea. I had to yank petunias frequently. I do love these though.
Karen
