How to Control Temperature?

[netrizone]

Hi all, the temperature in my area has been dropping very low in recent nights (10C/50F), which I'm afraid may be affecting my phals.

I've tried seedling mats, but they heat up the area very minimally (only 2-3 degrees F).

I've also tried ceramic heaters, but the plants closest to the heater tend to become very hot, while the ones further away don't experience much of a temp increase. Ceramic heaters also tend to draw a lot of humidity from the area.

Are there any other ways to raise the average temperature of my phals? Right now, they're all huddled together under a grow light in a corner of my room.