At the last count I had 105 containers with growing crops in them and I've yet to pot up most of the tomatoes and all the peppers, cucumbers and aubergines. This has only been possible because I make my own compost.
Last year I bought a big tub of pelleted chicken manure and one of BFB and these are the only commercial fertilizers I use apart from some tomato feed for the greenhouse crops. I do make a lot of seaweed tea, nettle tea and various other smelly concoctions and gather wood ash from various burning operations hereabouts. I really like the idea of a closed system where very little is brought in from outside and as much kitchen and garden waste as I can get hold of is composted. I'm even now recycling the compost from the first container of potatoes that I emptied last week. With a little added BFB it's now home to some lollo rossa lettuce transplants and when they are finished it's going on the compost heap. I can sometimes get three crops from the same compost but potatoes are very hungry and there is not likely to be much left when they've finished feeding!