A soggy welcome from soth TX welcome to the forum.
some varieties cannot take cold temps below 40.I don't know what kind you have.so going on the posibilty the person who gave them too you KNEW your conditions by saying "dig in winter".they go semi dormant in winter.they stop
growing or slow down growth below 50s& some 40s.if have
greenhouse can provide bright light and grow on but water less letting dry completely between waterings.or can dig and wrap roots in burlap and store in cool dark place,but not freezeing temps.if parent has pups dig leaveing pups attached to parent and then in
spring can seperate pups from parent.they will get nourishment from parent over the winter being attached.
Hope that helps.I have hardy ones which stay in ground.you can look at Ty Ty nursery online.they sell lots of bananas and show pics of all they grow and have the grow info and maybe you would recegnize your banana from their site.also gives blooming& fruiting info.