i can tell you what sterile soil is....well atleast what i heard to do if you don't want to spend the extra money to buy it.....you take the soil (acutal soil not outside dirt) and you bake it in your oven on 350 for about 20-30 minutes....and ph is a test thing....and they shouldn't be that much maybe a couple of bucks....and you can buy ph tests at any petstore that sells fish...