5 parts peat moss , 3 parts perlite, 2 parts worm castings or compost, 1 cup powdered dolomite lime per cubic foot as a ph buffer. If you use a 3 quart container for your parts in the mix above, you will end up with exactly 1 cubic foot of mix, which is about 7 gallons of soil. this is your base mix, it contains few nutrients, so you will need to add some, It can be as simple or complex as you wish. I did a seed run with some autos using the above mix adding 4 cups Espoma Plant Tone per cubic foot of mix, which brought them well into flowering before i had to supplement by topdressing some flower tone by espoma. if you don't want to use espoma (it is organic) then you can add stuff like blood meal for nitrogen, bone meal for phosphorus, and greensand for potassium. I would recommend adding a cup per cubic foot of espoma biotone starter PLUS for beneficial fungi and microbes as well. If you go the route of using Plant Tone, you will not have to wait to use the soil, but if you add blood meal, bone meal, etc, it is best to let the mix "cook" for a month before use to allow the microbes a chance to multiply. I recommend the biotone starter plus to be used either way, for the beneficial fungi and microbes it contains.