Well its winter here in Massachusetts, it getting to 12 degrees here tonight. I put my 1 year old figs in the garage, it gets almost as cold as the outside, these are cold hardy varieties and I checked today and there still living. I am kinda worried though it might get too cold in the garage. It has no isolation and it is next to my house. My basement it too warm for figs with my big furnace. It stays a toasty 70 degrees there.

I think 12F is too cold, but I live in paradise. I would assume they should at least be above freezing.

My garage has gotten to -14 c with figs surviving but they were deep into dormancy.  You may want to cover them with blankets if you don't have a safe heater for them.  You can always make a box with plywood or cardboard to encase them more too.

Yeah, 12F is too cold. It's 22F at the moment and I know some of my container trees will suffer but if the temps drop to 12F they will be a gonner.

We expect low of -16C ( 3F) tonight. It is already  8F ( -13.1C). I am using a small ceramic heater to maintain just below freezing (for cost saving reason). I will make sure it does not go below -5C (23F) except for short durations when garage door needs to be opened for short duration of less than 4 to 5 minutes.
That is my paradise !!

If it has electricity I think would invest in a space heater. you can pick one up for less than $20. Is your garage poorly sealed?  I would think The containment would  moderate the chilling for overnight type cold. Extended cold would eventually bring it close to the outside temp.

My detached garage got down to 25 deg last night with outdoor temps at around 21 degrees as a low.  It's hard to know how cold is too cold because there are a lot of factors in how much damage the figs will get.  I like the blanket idea on some of the younger ones. Some figs have quite a bit of green wood so I suspect I will be pruning that wood off come spring.  I'm also thinking of investing in a space heater for occasional cold nights if this winter turns out to be colder than the last few have been.

To expand a bit, what I have heard is that it is not only the temperature but the wind, especially dry wind, that is an important factor.  So generally speaking, I would think figs in a well sealed garage should be able to withstand significantly lower temperatures than those in the outdoors.  Then again, you don't want the rootball to freeze.  I'm sure others in colder areas are more knowledgeable on this than I am.

Space heaters  and/or Christmas lights.  I use regular rope lights because they don't get hot enough to be a fire hazard.  For your situation I'd put blankets then a tarp over the plants.  Some varieties don't like it below freezing and will die.  You may just have to let them go.  I had one that I collected wild from N CA and it couldn't take temps in the 40s - upper 30s and eventually died.  It was a pretty good mission variant - huge figs, taste like jam, very thick innards.  I know right where it is so if I ever get there in Aug - Sept again I'll nab another few cuttings.

i'm not in a paradise, but garage works for me here. then again, we don't go more than 10F outside, and my garage is usually 10-15 F higher than outside. with south facing wall, it gets warmed up nicely as long as sun is out. we've hit below 20 already this yr. weather just sucks.

I am with Ottawan in post#5...

I did same thing, an unheated garage (wish it was much bigger!),
e/w with a small ceramic heater and an external (expensive)
thermostat set to kick in ~@32 *C - just enough to keep
inside cosy temp @  min. 20 *F.

Also make sure pots do NOT run bone dry.
Add water/snow if needed.

George, can you post any links to the type of thermostat one would need for this purpose - thanks!

Here is my experience over many years in attached garage which does get into the teens each season and 1 season at 6 to 8 above when we had near outdoor record lows of minus 23 below zero.

The elders sitting on garage floor do fine no protection except that 1 season when it was 6 to 8 above i threw some bedsheets over.
The 1 gallons i have seen them either die to soil level or perish.
Fortunately i do not have anymore that small to store anymore.

Martin, it's good to hear that your figs can withstand temps down to the teens or even lower.  You grow some varieties like Black Madeira which are not known to be particularly cold hardy so that's also reassuring.  I have a couple young figs in 2 gallon containers but I placed them inside of 5 gallon buckets and surrounded them in mulch for additional protection.  Fingers crossed.

Well, the weather jockey was right. Temps reached 19 this morning, just like he/she said. Last night before it got too cold, I added a heater and turned it on. Temps did not reach 40 inside my GH. I am so happy! Last week, I caulked it real good to keep the heat in and it worked.

My garage is insulated. Temps there did not reach 58. So far so good....

Sounds like your garage is attached to your house ? "...and it is next to my house..."
If that is the case, then the warmest place would be up against the shared wall.
Depending on how many fig plants you have in your garage you could build some sort of shelter
up against the shared wall, and the figs would get some warmth coming from your house.

No damage to them at all. I checked today. It only got to 18 degrees last. The coldest we have seen. I will put a blanket over them. If it gets to the lower single digits I will take them in my basement. In 2 more years I plan on having these figs in the ground without protection on the south side of my home. Where it will be much colder than my garage in zone 6a. But in that spot I picked out it is a defenently a zone 6b. I am about 20 miles away from 6b so I may be looking at a zone 7a in that spot soon :) I only dream about that day.

Going to 23 degrees in Albuquerque tonight. My potted figs are in a small shed with a heater that has a thermostat on it, set just below 40 degrees.