You'll find every ratio under the sun out there when it comes to soil mixes....
Personally i just threw in 50/50 Top soil, the other 50% was a mix of Compost soil and cow manure...
All 3 of my plants took off like gangbusters, netting me over 1# dried the first year so something worked...but then again i live in Oregon im pretty sure i could have put planted them in a pile of garbage and they would take off.