For containers, you should use a soil-less medium, and most of them are peat based. The only potting medium I use, at present, uses conifer bark as the main ingredient along with peat moss, and perlite. Commercial potting mediums will be pH adjusted, and will contain either calcium or gypsum. I have, in the past, mixed a very large percentage of bark fines into a regular potting mix, and have been happy with the results.

Whatever you do, don't put a shovel full of your best outdoor soil into your containers. Even the finest garden soil turns into something awful when removed from a soil SYSTEM and made to live within the confines of a container.

Yeah, garden soil and potting soil are two very different things (I know, it sounds silly to say anything beyond "dirt is dirt", but there is a lot of bio-chemistry going on in there you can't see).

Walmart has started carrying an "organic choice" potting mix from miracle grow that is pretty excellent, IMO. Its not the standard dense black soil you're used to seeing from them, its got lots of shredded bark and is overall fairly light and fluffy even. Very good drainage, does not appear to compact much over time (so far that I've seen, YMMV), all around good stuff so far.

I grow peppers in the ground. The best growing site here in my NH garden has been the south side of our white house. I think it's much warmer than in the open garden. I've heard some gardens use a stone mulch which I am going to try this year in the open garden.