They got here and they've been working out great! I unboxed them and it gave directions to turn them from cooling to heating thermostats, so I assumed they were wired for cooling. I spent over an hour trying to set it for my swamp cooler to finally realize it wasn't working right... I rewired it and it worked out well. Since the cooler thermostat is in the sun, it cools down much slower than it should, so it turns on at about 82F and turns off at about 72F. The heater has been keeping the greenhouse exactly 54F at night which is nice. I don't have to go out in the dark and set it anymore.
Thanks to all who helped!