You probably shouldn't ask me. I've always used Sunshine Mix until this year. I couldn't find it anymore, so I bought Miracle -Gro/Moisture Mix. I can't be sure, because we're having a severe drought here, but I don't think Miracle Gro is a good medium for me. The plants that I repotted in MG aren't not doing well. I bought more Perlite today and I plan to re-mix the soil the Medinillia is in with more Perlite.
I think Carole here is our expert on growing these mysterious plants. Hopefully, she'll chime in. Sandi