I've been "vermicomposting" for a good while now. It's simple, takes up little space, doesn't smell (if you do it right), and it provides me with gallons of free castings. The type of worms I use are "Red Wrigglers". I keep them in a big "Sterlite" tub with holes drilled in the bottom and the lid, in a dark corner of my flowering room. The extra CO2 generated from the natural process of decomposition, which the worms help facilitate, doesn't hurt my garden one bit. When I harvest the castings a few of the worms of course get mixed in, but when they're in the container, by nature they know to avoid light.They stay just below the surface. As long as you water your plants properly(not saying that you don't) the little guys/girls(worms are hermaphrodites) should hang around for the rest of their life cycle which can be up to a year or more. I keep saying that I'm going to write an article for HT on "vermicomposting", but "stoner-complacency" prevents me at the moment.