This is the wrong forum for that topic but I would suggest using a better draining soil and not keeping it too wet. Adding perlite helps but IMHO you will always have an odor when using organic base soils. You might also try adding some course sand. You could also try leaving a window open and/or adding a fan for air circulation.

I second that suggestion-- don't keep it too wet. Let them dry completely between waterings, don't cover them, and keep a fan blowing.