Recently we bought a bag of organic potting mix from Walmart. It was the Miracle Grow Organic Choice (Container) Potting Mix, which contains sphagnum peat moss, partially composted wood chips, and chicken litter (.10/.05/.05). It’s a bit expensive at 16.8 lbs for $10 ($.65 / lb. w/tax), but it works well in our bucket garden (chicken litter – wear gloves). Then a friend of ours sent us some of his worm castings. At $28 for 30 lbs. (free shipping), it’s a bit more expensive ($.93 / lb), but it’s local, small business, and more sustainable (no peat moss and no chunks of bark). We are setting up additional buckets of tomatoes and lettuce, and will keep you posted on our progress. We have used worm compost in the past, with fantastic results.
Check out Jeff’s work at http://organicandmechanic.ecrater.com/