I've used regular Miracle Gro potting mix before when I was tight on cash. It works fine if you dont add anything but water to it for the first 3 weeks. It doesnt drain very well, so maybe mix it up with a little peat moss and perlite, but its not totally necessary. A lot of people say how bad MG is, and they probably have never even tried growing with it before. Ocean forest is definitely the best, but MG will definitely get the job done for now, as long as you dont overfeed it.