I would recommend that you take a look at some guides. If you area asking these kinds of questions then you haven't done enough research. When I started I did a lot of research and still when i went to grow nothing could prepare me fully for certain obstacles. Take your time and read up. Depending on the contents of the potting soil and the pH of the compost you might be able to make it work. Or you could spend less than $10 and do it right.