I have not had this problem. Does your garage typically get mice?

Knock on wood, not so far! And I certainly don't want that to change. But if you Google search "mouse fig tree garage" (no quotation marks) you will find a couple of worrying stories. And this article in particular: https://awaytogarden.com/how-to-overwinter-a-potted-fig/

Mice would be very low down on the risks to your fig tree. Not a reason to worry or to give up on growing one. There are plenty of ways to protect from these hypothetical mice but a plastic bag isn't one of them.

and in z5 the plastic bag will serve no other reason along the lines of winter protection ...

on a zero degree day in jan/feb in z5 .... if you open that garage door .... once or twice a day ..... your fig is going to have a hard time surviving ... and the plastic will add nothing ....

i might think that mice are the least of your concerns growing a fig in z5 ...

but of course.. you have to try to do it... its the only way we learn ... and keep us posted ...

ken

ps: are figs deciduous??.. i dont have time to look it up ...

In case it wasn't clear, the bag is primarily to make sure it is consistently dark for the tree, not to provide insulation. Yes, plenty of fig growers around here, and I even have some relatives who go to the trouble to bury the tree underground in the winter time. I don't have the patience for that, so in the garage it will go. Happy to hear these trees are generally not mice magnets!

The problem isn’t rodents taking fruit but girdling the trunks of the trees in storage by knawing on them

A dormant deciduous tree doesn't need to be kept in the dark. After all it wouldn't be kept dark if it was out in the garden. All it needs is a temperature low enough to keep it dormant.

Some people like to make comments on topics they have no experience with :-)

==>> and some people are just down right rude ... and i dont care about your colon smiley face .... why cant you just respond without attacking someone???? .. you could have easily made your point without such ....

this link states: Zones6-10, may survive as low as zone 5

https://www.epicgardening.com/chicago-hardy-fig/

so it all depends on HER z5 ... her garage.. and her pot.. media.. how often the door is opened .....etc ... i was just explaining it still a roll of the dice in z5 .. and a plastic bag wont change any of that ...

whatever.. im so tired of being denigrated by certain responders .. and then you all wonder why GW isnt the happy palce it used to be ..

ken

https://duckduckgo.com/?t=ffsb&q=denigrated&ia=definition