I undertook a similar experiment this past winter here in southeast Connecticut, where the temperature dipped as low as -12°C. My much-beleaguered fig survived well, but had the weather been like the previous year with 2 consecutive nights of -22°C, colder than I'd ever seen here, it might not have pulled through.

I've posted about this elsewhere, but I planted the fig a little deeply, near a south-facing garage wall, wrapped the little tree in plastic, filled that space with a combination of dry peat moss, sprinkled with crushed red pepper to keep out vermin. A tarp was laid over this, secured with rope, tucked in at the bottom and weighted at the edges with soil.

I've seriously considered using a warming cable, and glad to hear it worked for you! I had thought about making a good cutting of this fig, and in the course of unwrapping it, a dormant, live 2" twig was knocked off. I wrapped it in moist paper towel, almost up to the terminal bud, sealed it in a plastic ziplock bcag, and placed it in moderate light. A month later, it's developed a few small leaves, and while there are no roots yet, it has 'nubs' developing near the cut end, which hopefully will develop roots! it has a small shock of leaves too.

Ken, let's keep each other posted of our ongoing results!

I also experimented with an in-ground Chicago Hardy this year in Zone 6. I didn't do a damn thing to it and left it exposed to the elements. It died. Or at least the entire portion of the tree above ground is dead. Hoping that it grows back from the roots so I'll wait and see. Any maybe next year I'll try to protect it.

two days after it leaved , temperature dropped to -2 C overnight and it snowed..i left it exposed and the leaves turned brown ....it hasn't grown back in that spot since...it really doesn't take direct exposure to the cold very well, even at slightly below zero temperature for a few hours ...it needs to be covered...but luckily, it wasn't cold enough to kill the entire tree....leaves are coming back now at other places, just not that same spot

As long as your heating cable is functioning and you have some insulation, theoretically, it should keep it above freezing ...i didn't even plant mine deep...probably just an inch or two deeper than the tiny planter it came in....there's no way i would dig it up every fall and bring it indoors...it's too much hassle and I want it to grow big and get hundreds of figs..

Hardy Chicago grown in 30g container for nearly 10 years as single trunk tree.

Planted in ground in wide open space with no protection always died to soil level and sprout back up to produce figs very late now grown in bush form in ground.

Here is picture when this particular winter was colder than usual with temp gauge and picture of HC .

Coldest that season was 21 below zero Fahrenheit with many many winter days below 0 and thus breaking records here near Chicago.

Good thing plant was an elder.

Following season thought it was dead but did sprout back up early summer thus producing no ripe figs following year it did.

Now a days throw tarp over it and produces figs a little earlier , still has die back but not as bad.

Pictures date stamped.Thermometer on house brick wall facing south both pictures taken 1 minute apart it was very cold despite quickly taking picture that morning.

Martin

giving you guys an update...my fig is starting his 3rd year and he's never stayed indoors ever.....

the temperature dropped to -25C (-13F) back in january here...there were a few days around minus 20C...and he survived ..

heating cable + pool noodle + tree cover with some dead leaves did it again

hopefully, when it gets really strong with a big trunk, i can stop winterizing him...

want to try this on some zone 6 / 7 trees..