i use Whitney farms organic potting soil. i add 10-20% perlite for better drainage. NPK is 0.15-0.10-0.10. the soil isn't very hot but it says it "feeds" up to 2 months. i start my plants on general organic nutrients at week 2 of life at 1/2 strength. i'm happy with the soil. i would recommend that, or i would go for the happy frog soil if you're looking for something light. whitney farms was just a bit cheaper on ebay. if you're looking for a soil that's a little hotter i would go for fox farms.