Ken is most likely on the right track. Here in Meridian, Mississippi, petunias of any sort rarely last much past June, because they do not like the extreme heat we get in our summers. This year, June was really more like August, so petunias did even worse. I am guessing that your plants that survived were getting enough shade during the day to allow them to hang on. Next year, maybe you should try white Vinca or White Profusion zinnias or even a white Penta in front of your roses. If they are getting all day sun, these are highly likely to be star performers the entire season.

I have both Nicotiana sylvestris and a short pink one. Do you still have seeds for blue shrimp plant and/or still want to trade? Thanks. Marcia Here is a link that might be useful: trade list

Sorry, never grown them but here is a link that might be useful: wild white petunia (Petunia axillaris) at Annie's Annuals & Perennials

These are the Wave Petunias I have with my Knockouts, not sure which color is which. The lighter colored ones are not white, they're a very light liliac looking color.