In the book Grow Figs Where You Think You Can't, I tell readers that, even if they're in a place where a fig can't stay outdoors over the winter, their fig tree is easier to overwinter than a houseplant.
Here's what I say in the book:
Let’s get things in perspective before we begin looking at ways to overwinter fig trees in colder climates. Over the winter, your fig trees will need no more care than a potted houseplant—and probably less, because they go dormant.
I break down overwintering tactics into two broad groups: indoors and outdoors.
Easy Because Figs go Dormant
Fig trees are deciduous and drop their leaves after first frost. This is great news for gardeners because it means we can keep them over the winter even if we don’t have a bright, hot greenhouse. While they’re dormant, they don’t need light or much heat. In areas where figs won’t normally overwinter outdoors, this dormancy means they can be stored inside, or, in many cases, outdoors with minimal protection.
The key is to keep the plant in a dormant state as long as possible, by storing it in a cool, dark place, Active growth indoors, in low-light conditions, will give weak, lanky growth.
Read the book for tips about overwintering outdoors using an A-frame, arbour, insulating techniques, and burial. If you want to overwinter your plant indoors, learn about what sorts of buildings and places indoors you can use to overwinter your fig.