Lys, are you certain it's an annual? Could it be Rose of Sharon? Toni

Hardy Hibiscus perhaps? Their flowers are eight or nine inches across.

Here is a link that might be useful: {{gwi:1052481}}

If it is an annual-it may be lavatera-the flowers are smaller than a hardy hibiscus-and there tends to be more of them,

Here is a link that might be useful: lavatera

Maybe they are Petunia's?
This was the first plant to come to mind.
Tina

Lys, I've two hardy hibiscus..flowers differ from each other..One has red, 10-13" dish sized flowers..The second is white w/pink inside 7" flowers..both are hibs but do not resemble...Also leaves are entirely different..if I didn't know they were hibs, I couldn't ID them..(S) Toni