Hot to gather frostbitten Mexican Petunias? I moved from FL to MO in October. I be keeping some...

I moved from FL to MO in October. I be keeping some Mexican Petunias in the garage - they're z8 plants - and they get frostbitten pretty bad from the cold weather on monday and tuesday. It get down to -5 w/ the windchill and I guess it wasn't safe/warm enough contained by the garage. Does anyone have any guidance on how to save them? We brought them within the house yesterday afternoon. The soil in the pots be practically frozen. We put warm dampen on them until it thawed.

I basically read that you shouldn't fertilize frostbitten plants for 1yr after you see new growth and not to remove leaves unless you know for sure they are comatose. I also read that you should trim stuff down of it is really bad. So....Idk what to do or even if what I enjoy done so far was the right article to do. I also gave them some Rescue Remedy (silly, I know, but I purely brought these up w/ me in October from FL - I have rooted them from cuttings in my yard).

Thanks for any abet.
How and when can I increase my herbaceous...
Answers:    I live in Phoenix and it get really cold here last year...probably within the 20's, which is probably what it was IN your garage. I did zilch to them and they came rear this year like nil ever happened to them. They are a remarkably hardy plant. Don't cut any of the frozen parts off until spring and don't forget to hold them out of the garage....they do need some sun. :-)