Any ideas on how to keep these guys warm?  

The cold winter air is seeping through the windows and the room cools down to the 60's at night.   I've noticed their growth has slowed since it got really cold in the last few weeks.  

I've got a heating pad underneath the cookie trays hooked up to a thermostat, but that pad is only 19" and doesn't reach all the way over.


  

I have no firm evidence of how much difference this makes, but I wrapped my potted fig trees with aluminum foil. They seemed to retain more heat (noticeably warmer to the touch) and are sitting in a very sunny windowsill. This might be overkill with a heating pad though...not sure. Seems to be working really well with the window though.

I also have plastic wrap stretched over the top and secured with a rubber band (creating a greenhouse effect). Just use two pieces of plastic wrap, one stretched around each side of the trunk so that next to no humidity escapes. Between the plastic and aluminum foil, the heat builds and stays put longer. I have only been growing figs for a year though, so take this with a grain of salt :).

I put them directly on heat pad and wrap a couple towls around pots and make sure any exposed heat pad is covered up with towl too. Try it for a few hours,makes,huge,difference

A few members are putting a space heater close to their figs. It'll dry the air but you can mist and water correctly.

Heavy curtains that can be closed at night may make a difference. 
I also have roll down shades on the outside that I unroll at night that cuts the wind.

Interesting idea about the windows.  If I put plastic wrap over the windows (from sill to ceiling), would that create an insulation?

think I'll give the towel idea a shot as well. 

Thanks. 

If you set the heat mat on top of a piece of foam insulation, a lot more heat will end up going to the plants, instead of heating up the countertop so much.

You could also tighten up the trees, you have plenty of room.  That way all 3 will be on the heat pad.  

I describe my new setup in my rope light thread. A light for heat in a cooler, under a tote for a humidity chamber. It's been working well. I open it up for light during the day, unless it's a really cold day, and put Styrofoam over it at night. That's an AC window unit behind it, and you can see snow up against the window over it. If you already have a heating pad use it, but do insulate under it. Getting a tote deep enough can be a trick... But you can turn one tote upside down over another to make a big chamber.

 

Where is the probe for the thermostat?  Is it in that pot all the way to the right?

The Thermostat probe is indeed to in the plant all the way to the right.  

I will put foam under the heating pad, seems like that would work.   However, I still plan to keep the cookie sheets on top of the heating pad because they act as a catch basin for when the water drains from the pots.