If you want pre-mixed soil, go with:
1) Roots Organic: Original Blend
2) Fox Farm: Happy Frog
3) 1 part Fox Farm: Happy Frog, 1 part Fox Farm: Ocean Forest
If you want to build your own:
1 part Worm Castings
1 part Sphagnum peat moss
1 part Aeration (Pumice, lava rock, perlite, rice hulls)
2 cups BuildASoil: Craft blend per cubic foot(7.5 gallons) of medium
1 teaspoon BuildABloom for every square foot(4 square feet in 1 cubic foot)
1 handful of composting worms per cubic foot of medium