I just use regular potting soil....or in a pinch garden soil....and given enough sun they do very well.
Linda C

I put several in pots with standard miracle grow potting soil. I also put several into the ground in not so good soil with mulch around. The one's in the pots are doing much better. Put in a sunny place.

Yes, that's the answer i was looking for - I remember last year when I put the waves in the ground, they did much better with richer soil. I am going to use the regular potting soil for the pots and add some good compost to it - I think petunias like rich soil... but then again, some have had good experience with "poor" soil....

Carrie

Get a bag of miracle-grow soil or similar and they'll be fine.