Hardening off has been an issue for me. Either I forget the plants are out there and leave them too long, or I take too long getting them in and out to make time measurement a very sure thing. To try to combat this, I purchased a surprisingly cheap steel kitchen rack that should fit all seedlings being hardened off at any given time. This way I can push it out into the drive way each day, set an alarm, and push it back in when the alarm goes off. Easy right? What could possibly go wrong?