Turn them a minimum of three times a day - five is better - but always an odd number of times. It's easiest if you cut the tops off an egg carton and hot glue it to a piece of 3/4" or so PVC, and just lean the carton from side to side.
You'll have much better results if you can put an old pc fan into the still air. Lots of instructions on here how to go about doing that. Search pc fan.