I have yet to grow a petunia that wasn't toast by mid June, but you have very little to lose. If you try it, and succeed, by all means let us know what kind of petunia it was.
I grew petunia integrifolia several years ago, and although it burns up by early summer, it seeds back each spring and I enjoy it for free for about eight weeks each year. That's pretty good, I think.

This is one thing I always read and never understood. Most of the people in this forum say their petunias usually die back or stop flowering by mid summer.

Well, here where I live summer weather lasts for about 5 months and my petunias always look good.. but they do need a lot of maintenance. I water them everyday, fertilize weekly and deadhead regularly. Everytime a plant looks "leggy" I cut them back and they'll flower again in a week or two.
They all get about 6 hours of sun, from 7am to 1pm. Afternoon shade makes a huge difference. Plants in the ground always perform better than those in containers, so the bigger the container (or the hanging bag), the better.

Of all the petunias I've grown from seed, the best performers are:
Tidal Wave Silver
Wave Purple
Easy Wave Blue
Shockwave Ivory
Tidal Wave Cherry
Prism Sunshine
Ramblin Burgundy
Wave Misty Lilac
Opera Supreme Lilac Ice

Mauricio

Totally different zone here, but thought it worth commenting anyway. Usually around end of the July (which is about 8-10 weeks after planting out, weather depending) I cut back the petunias because by this time they are flowering less and lanky and dare I say rather ratty. I cut back by about 2/3 or so, but stagger the cuts a bit. In a very short time the plants fill in again and flower beautifully.