I spent some time this afternoon riddling compost to get some nice fine stuff for the containers. I put it through a sieve with a quarter-inch mesh and the bigger stuff that's left goes as a mulch around fruit bushes, etc. To the half-barrow of compost I added one bucketful of mole-hill soil, one bucketful of cheap growbag material, some vermiculite and a scoop of bonemeal. When mixed this gives a light, open growing medium with a pH of about 6.5 which is ideal for most of my container crops. The base material can be adjusted to suit various vegetable types by adding fertilizer at the potting stage.
For instance, carrots and parsnips get the basic mix with some sharp sand added but most other crops get blood, fish and bone meal with additional liquid feeds through the growing season.