I saw this thermostatically controlled outlet adapter and wondered if it would work to help inground winter protection on those really cold days? The TC-2 unit turns on at 20F and off at 30F. My thinking was to have this inside the tree (pruned to 3 feet or so) that would be wrapped with plastic lined burlap (old seed bags) and plugged into a low output heat source item such as christmas lights or the smallest single incandescent bulb possible. Insulation would be added around the wrapped tree and then wrapped in a tarp. You could run a cord from this plug out to another tree and so on. I planted 4 figs in my greenhouse this summer and thinking of trying this since its unheated. Next year I plan on planting some outdoor inground also.

Do you think there would be any shortfalls to this method?? I obviously don't want to create a fire hazard so the right heat source would be important. I would think that the outside temperature would have to dip to below -10C for the tree cavity to hit -7C for the heat to turn on so I don't think it would be on 24 hours a day all winter. I guess the amount of insulating would dictate how efficient it would be though.

Any thoughts? Is 20F too cold for most fig varieties???

Here is a link to the product:
http://www.amazon.com/Farm-Innovators-TC-2-Thermostatically-Controlled/dp/B000M4ZJ6Y

It seems like a good option, and one that I could use in my unattached garage; however, it seems like it would be best not to let the temperature drop below 25 degrees F if possible.  If you find one that turns on at 25 deg F then let us know!  Then again, for relatively cold hardy varieties keeping them above 20 deg F will probably be fine.

The TC-3 unit from thermocube turns on at 35 and off at 45. I read some reviews though that those temps were actually higher (on and off) which I thought would be a bit much. If this units temps were also off by a few degrees higher it would be better for sure.

IMO if the temp range of adequately protected in ground figs is maintained at 20-35F the main trunks and older branches should be fine for cold hardy type figs.

Hardened mature dormant Figs are supposed to take 16F.   Of course that does not mean that the little brebas nor the young tender shoots will survive.  

I have been covering my in ground figs minimally for years with no added heat source.  The main branches have survived fine the tender shoots frozen off yearly.  The overall ripened crop level have been high.   But lots of unripe figs left over since in the past I haven't had time to pinch the shoot tips and knock off the small figs.  This year I have pinched and thinned and I am finding the figs are coming along more uniformly.  Should start ripening soon. 

Do you know how these devices react to high humidity and possible moisture under the covered figs?

Pino.. that I am not sure of how they do in humid conditions. Are your trees wrapped tightly or can they breathe???

edit... in the description from the amazon.com link it says...

• Ideal for home and farm applications such as pond de-icers, unheated rooms, pump houses, greenhouses, boats and RV's

If you use the 20-30F, just keep the device near the base of the tree, which will cool faster (heat rises).  You can also use in conjunction with heat tape made to prevent exposed water lines from freezing.

I am going to use one of these in my shed where I plan to keep my trees.  If my figs can't handle 20F, then I don't want those varieties.

Pino - humidity should not be a problem, but obviously getting an outlet wet could be.

Tyler , 
I secure with cinder blocks a poly cover folded over 2- 3 times.   The poly I have been reusing for many years so it has tears and holes.  So yes air is circulating because you can see the poly go up and down with the wind.

This adapter sounds interesting.  As Phil said as long as outlet doesn't get wet.

I wonder if a roof/gutter de-icing kit can be adapted to use with this thermostat adapter for in-ground figs? 

http://www.canadiantire.ca/en/pdp/roof-de-icing-cable-0522580p.html#/en/pdp/roof-de-icing-cable-0522580p.html#.VAifrLHD8yU

Tyler,

    I garage mine, but this is what my cousin does (and his cousin does) and we are all in the same zone.

Gene I think that model would be great for a shed or unheated garage for sure. In my zone though using that one in an inground tree application might be as cost efficient as our outdoor hottub we keep at 100. Yeah don't ask me about THOSE hydro bills lol. Especially this past winter lol.

Tyler

Just an update the last 2 nights we've had -11C (12F) overnight lows and I have a small space heater plugged into the TC-2 unit in my glass greenhouse. It seems to work well to keep the temps at or above 20F. My inground trees in there are wrapped in burlap to hopefully give them a degree or 2 more protection.