my soil was that miracle grow organic soil, then i mixed in 1 bag of peat moss and about 2 bags of perlite/vermiculite(foam rock in my case), couple scoops of chicken shit. mixed all that up in rubbermaid bin and let it "cook" for a week or two. check the ph and if its 6.5-6.8 range then your all set.

need to do some soil conditioning to my soil bin though since its a lil hot with ph of 7.4. gotta add more peat and let it cook down.