Well, yes and no. If they have protection from the sun in the hottest part on the day during the summer, they will wilt but come back in the next morning. They look terrible while they are wilted, but will come back and look just as pretty. So they will survive and bloom during the hottest months. So plant scads of them on the shady side of the house and where they will be protected from about noon on. Forget about the west or south side of the house. Of course, as soon as we have a frost, that's it for the winter. They keep growing so that at some point, you may want to cut them back a little. They are easily rooted for new plantings too.

Thanks agnespuffin, I'll put some in...they'll be well shaded except for early morning and on an irrigation system. Hopefully they won't wilt TOO much in the afternoons.
This is a *huge* new garden going in this year, all along the picket fenceline of the back yard under good tree canopy (we back into woods). My first woodland/shade garden! Always lived where there were only fun sun gardens...

Keeping them well mulched will help, too. You'll see this summer that Impatiens is ALL over the place in Savannah.