What kind of ground surface to practice HS?

I realized that gymnastic floors are softer and bouncier, and i think most of gymnast practice on that kind of surface? but normal people are doing it on solid ground, so i'm just wondering, which kind of surface would be better to practice it? or does it even matter? the softer ground DOES feel harder though

A hard flat surface is the easiest so go with that for training.  Experimenting on other surfaces isn't a bad idea but I consider it play, not training.  Gymnasts practice on the floor they will perform and compete on.