I'm on day 5 of a hardening process for my seedlings. It's been mild (60s-70s during the day) here. I'm going out of town for a few days, during which the temp is supposed to be 50-60 night-day. Should I leave the seedlings outside for those few days (under an overhang, no direct sun or rain), or will 50F be too cold? This would be day 7 of the process.
Well, yes, it will be a bit too cold - minimum temperature should really be 60 deg F. Perhaps you can arrange for someone to pop in and cover them in the evenings, otherwise you might have to rig up some sort of more enclosed, transparent shelter for them.
I actually had my heater quit and all my tomatoes froze but my cucumber seedlings did fine. If anything cover them with row cover. That will bring their ambient temperature up at least 10 degrees and they should be fine.