My thoughts (I'm northwest of Nashville) are that there's not much use in covering anything. I've tried to plant things that were appropriate to my zone. The couple plants that I knew were "stretching" the zones I tried to plant in sheltered areas. If they go, they go, and I'll learn from the whole deal. My "big guys"--trees or larger shrubs that I spent more than a little money on--those guys are all hardy enough that they should shrug this off. (Or if they don't, why then I'll learn to cover them next time!) ;)

Rereading the original post, I think the original poster DOES NOT have a heat pump, but the thermostat downstairs thinks he does. Maybe it needs to be reset and reprogrammed. I have a honeywell touch screen tstat that's capable of doing hybrid, etc but I currently only have gas forced air heat, however, I'd bought a NOMA programmable tstat which had a lot of features I liked, but when I hooked it up, it would control the fan ok and would act like it was calling for heat, but heat never happened. If I jumpered the terminals, the furnace would behave normally. Rather than persist with it when it was getting cold and dark on a weekend with no NOMA technical support available, I just went and got the Honeywell. It was fine after that.

SE Wisconsin: 3 or more inches of snow Friday night and Saturday morning. Sat: Colder. Several accidents on the freeways. North bound US 45 blocked, all lanes. A double bottom truck truck skidded and blocked both lanes. Traffic mess. Sat night: Windy, temp down to 15 F. Sun: High was 20 F. Streets and sidewalks have been cleared. Driving conditions fairly good. Predictions for Monday and Tuesday: Its going to be really cold: single digits overnight for two nights before it begins to moderate. Possibility for light snow on Thursday. WINTER has arrived!

Insulation in a basement or unvented crawl space belongs on the walls, not the ceiling, so start with that in any case. Besides the other steps mentioned above, check the ductwork, sealing the joints with metal tape--no, not duct tape--and be sure that there are no disconnected ducts. If your master bed is at the end of a long run, a booster fan may help. Also, check the attic for proper insulation. Old style potlights are massive cold spots.