Oh, and a tip -- don't be silly like me, and put your heating mat on a surface that'll heatsink all the warmth away. It took me a few days to figure out that I needed to put an insulating layer (in my case, cardboard) between the mat and my granite windowsill. Sometimes I am not so quick, ha. If your windowsill is wood or some other insulating material, you won't really have this issue.
Last edited by twinofmunin; 12-31-2016 at 10:17 AM..
Ive seen Youtube videos where a heating cable is laid under a bed of sand and plants placed on top of the sand. I guess watering the plants and sand would give a somewhat increased humidity.
This is a bit more involved than a plug in on a windowsill but as a greenhouse/shadehouse thing it might go some way to solve the heat/humidity issue.
Here is a link to one video. How To Build A Heated Propagation Bench - YouTube