http://www.motherearthnews.com/organic-gardening/container-gardening-zm0z12amzhun.aspx
"If rotted until black, either material makes a wonderful growing medium with excellent structure. Two parts rotted sawdust or chipped bark to 1 part compost usually makes a good container mix. If you're committed to growing container veggies, set aside a spot for these materials to decay so you can start making your own potting soil in the future."
There's a sawmill near us that's offering free sawdust and they'll even skip load it into our trailer.
I'm going to give this a try, as I am growing more and more in large containers, for a variety of reasons:
--The south side of my yard is narrow and gravel-lined. Peppers, tomatoes and other heat lovers really like growing in self-watering or other large containers there.
-- I can reduce the amount of solanaceae that I have to rotate through my beds if I grow my peppers only in containers (that leaves me tomatoes and potatoes to juggle in my raised bed rotations) and they do great in them.
-- I can tuck those extra artichokes or potatoes into the random sunnier patches of the yard when I am out of bed space.
I like that the sawdust is renewable and not particularly carcinogenic (vermiculite may have asbestos in it). I'm picking up extra containers as I find them at thrift stores, going for the Rubbermaids only, as the less pliable plastics become brittle and break in a year or so's time.
One easy way to grow in containers, at least the smaller leaf and root crops, is in milk crates lined with weed barrier (I"m using old bedsheets, for lack of a better material).
http://www.urbivoreonline.com/2010/07/22/diy-milk-crate-container-garden/
I try to grow in containers that are at least 5 gallons, both for root space and to minimize the chances of them drying out in less than a day.
And if you want to put more work into it, there's always these great self-watering containers to make:
http://www.seattleoil.com/Flyers/Earthbox.pdf
Happy growing!
