I'm a newbie at this too but I don't let it go below about 58 degrees at night (try to keep it at 62). I have a radiant heater out there (with a oscillating fan constantly circulating the air) and a backup forced air heater that kicks in at 62 degrees. I also have a back up to the back up (propane tank and heater if the power goes out).
I bought a remote temperature/humidity monitor with an alarm that I have set at 58 degrees. If that happens I run out there and see what needs to be adjusted (it's getting into the high 20s here some nights). The monitor runs off battery power so if the power in the greenhouse goes out I'll still be able to know if the temps are dropping too low.
I have everything out there but my paphs, phals, and masdes - the temp gets too high during the day for the Masdevallias and there is too much humidity dropping off the roof to safely keep my paphs and phals out there - too high a risk for crown rot.
Everything in the greenhouse is thriving under these conditions with tons of new roots
, growths, spikes, and flowers.