Also, I'm about to plant a few new things in containers, and I think I have a bag of miracle gro potting soil in the garage, but from a couple of things I just read on this board, I may be better off tossing the stuff. What should I use instead? (I don't know if I have the patience/time to make my own mix of all sorts of different stuff - is there anything commercially available that does a decent job?)

As for soil--the best soil for seed starting and growing in pots is Pro Mix BX. It is the only thing I use in my greenhouse. Small bags are expensive though. I buy mine in a 2.8 cubic foot bale.

I don't know if you have it in the states but Presidents choice magic soil is good. I wouldn't throw out your miracle grow. Instead I'd mix it with a regular potting soil. The big problem with Miracle grow soil is that it has too many polymers that hold water and it's easy to overwater. Spread out over a larger area though it would be OK