This is my first grow and I decided to use PRO-MIX HP, which is an organic peat moss based growing medium and doesn't need any additional nutes. If growing organic is important to you, I would suggest checking them out - I was able to find it at my local Lowe's.
Just a heads up: Pro mix is a soilless medium and has no additional nutes so you're gonna need some stuff. Also, not to split hairs or anything, but the wetting agent they use is not organic.
Yeah soil is not my forte but i do know that hp in this case isn't high power(high porosity). I've heard people recommend sunshine #4 over this, but I think you should check out rrogs organic thread in here.
I'm a big peat fan. Also leaf mulch. 1/3 of a good soil mix IMHO. The other thirds are aeration like lava rock, pumice, biochar, etc. Then the last third the good stuff that kountdown said. IMHO