My guess is it's a form of ruellia. I am very hesitant to buy from any source who doesn't include a botanical name when they label or advertise a plant, especially mail order ones, and super especially those who do not include an untouched photograph, far enough away to show the foliar part of the plant. If it is a ruellia, then I would be suspect of its winter hardiness in any but the warmer zones. I have kept a small line of seed-started ruellia alive in zone six, I can't remember the cultivar. It remains green only in the protection of my overwintering house. It dies back to the ground in winter in very protected outside spots and I'm surprised it even does that well. It doesn't ever make it to shrub status. Your "Japanese" petunia shrub may have completely different qualities if it is a ruellia, and I'm sorry I can't give you a better answer. Hopefully somebody else here can. If it were at all mainstream in my area as a hardy overwintering plant, I would have prolly seen it in my sourcing catalogues.

Tidal wave and million bells hands down. I am trying something new this year and pinching back my petunias (a lot!) in hopes I will have a bushier plant/full in the middle, not just a trailing one. My trick is part shade in the hot afternoon sun. Mine will dwindle off if I do not protect them in late Jul and Aug. Keriann~

I lost my seedlings, and wouldn't start those in heat, but plants should be ok if you keep them well watered. One pot fell over and not very many germinated. My daughter who worked in a nursery said they used 3 in I think a 12" diameter basket with a peat liner. Usually I have pretty good luck growing petunias from seed, but probably should start them in something else and transplant. Burpee has that gorgeous Blue wave petunia, wonder if it is really true blue? The problem with that one is that it may not cascade as nicely as the wave ones.

I have tried tons of diffrent types/kinds. And I have found that petunias are quite forgiving in the deadheading department. Some are "self cleaning" But with mine I have planted close together and then some with more distance between closer is better I didn't deadhead because I was collecting seeds so my face in the plant every other day.So if it needed "picking" at I would do it then. My biggest problem was cutting a healthly plant this I have trouble but I think I need to try it this year to get fuller plants. If you would posted this sooner I could've hooked you up with at 10 different colors of petunias but now I am almost out of petunia seeds. But swallowtail seeds garden does have quite a few colors and types to try including some self cleaning. Paula