I agree that most of the organic soil recipes offered are too many tubs of soil for 1 or 2 pots of plants. I decide to use some store bought organic. As I live in Maine it was easy enough to use
Coast Of Maine organic soil -
Stonington Blend. Another organic ready mix is by
Fox Farm. I'm pretty certain that there are others and likely some sources in your own home state.
The twist I introduced for my 5 - 7 gallon smart pots of
Northern Lights - is that I added some red wiggler worms directly to my pots. I bought a bag of 100 composting red wigglers and divided them up between my 5 pots. I'm about to harvest in the next week and the plants and the worms seem to be thriving. Occasionally I'll find a worm has escaped to the tray under my plants and those little guys live up to their names as trying to grab one of those wiggly things is a comedy scene. They are plenty wriggly and active.
After I harvest my plants I intend to THEN start a worm bin. The idea is to recycle and renew the expensive potting soil and continue the worm activity through to next season, at which time I can use this year's soil all over again. I will likely add some more worms to the bin. All through the grow, t
he only provision I have made for making certain that the worms have shelter and extra food is: I have mulched the top of my soil with some decayed grass and leaves, cut offs from my plants (
which I chopped up into small pieces) and an occasional sprinkle of corn meal, coffee grinds, thoroughly dry and broken up egg shells, and a few times I've added some thoroughly dry and chopped up wild mushrooms. Raining too hard to take photos today (
they are in a shed but the photo shoot requires I leave the door open as my shed is that small 
) but here for your edification and inspiration is one of my beauties as of this past Saturday.
Good luck with whatever you attempt. All worth the effort.
Crow
BUD CANDY