We mixed the following for our self-watering containers:
1/3 vermicompost or compost
1/3 peat moss
1/3 perlite
Added calcium and 16 ounces worm castings per container.
Added soil inoculant to water reservoir.
This mix worked great and when we dumped it out at the end, the moisture content was just about right.
Had no more blossom-end rot or blossom drop with the addition of calcium.

Here is a link that might be useful: Organic Potting Soil Mix

Sounds like it would work well if you were planting a bog.

The ingredients listed are inconducive to drainage, unfortunately.

Josh

John,

why can't you use one part perlite instead of sand?
It will still be cheap and might allow you to get away with a few weeks of growing.

Forget the vermicompost and worm castings, same thing, if you are looking for cheap, let alone it will cause quick compaction, and a pastiness to your mix..;-)

Mike

I had no problem with compaction or bogginess. These are self-watering containers I'm talking about, in that the pot draws up the water from a reservoir, you know, like the earth-tainer/earthbox design. Wonderful composition when we dumped it out to check after the growing season last year. Making your own vermicompost and not buying fertilizer is about as cheap as you can get. I reused the peat moss/perilite and added more compost. Even grew corn this way.

I had the exact opposite experience in my SWC with soil like this. The soil help much too much water, my tomato leaves were always curled. I added extra calcium and still had BER. Until about two years ago, I thought they did pretty well. Last year I researched and this year planted using a different mix - larger particles with enough peat to allow wicking - and my plants are much larger, the leaves aren't curling and they look happier. I keep track of yields, so it will be most interesting to see how this year compares to prior years.

Of course, just my experience.