Larry, I'm in Loves Park Illinois, about 1 hour west of Joliet,This is my first year growing Bananas and I have about a million questions on how to do things,I have Dwarf Cavandish, Zebrina Rojo and Gran nain, all in pots as well as several citrus trees, I found a great site for help with Bananas with a lot of people from Wisc. and many zone 5'ers. Check out Bananas.org very informative and helpful, Good Luck with your Basjoo, much more hardy than the ones I have, gonna have to get one next spring though, very attractive plants. :)

The main thing is to protect a diameter around the plant about three feet across, or even bigger. So if your mulch bag is really big, then that would work. But I'm thinking that you might not be covering enough area.

Good morning,
I have a banana that says it's hardy up into zone 5.
This my first year with this, I live in Decatur, IL
and bought this thing in the spring in Champaign, IL.
It was 1.5 ft. tall, I planted it in the ground and
at this point it is 11 ft. tall, 8 ft. wide, and has
put forth 7 pups some are 4-5 ft. tall.
The area that I need to protect is about 2 ft. wide.
I moved 2 of the pups to the front yard, so I have
now 3 areas to protect. I'll have to get the tag to
see what the variety is but thats in the greenhouse
at the moment.
Hal Warrick

I lost my basjoo last winter because I made the mistake of placing plastic bags full of mulch right on the plant. The plastic trapped moisture.

So I learned to keep only dry mulch or a towel close to the plant. This year I rigged up a large chicken wire cage which I filled with dry mulch. Then I covered the entire thing with plastic, staked down around the perimeter. I also used a fungicide this year, because last winter a white powder grew everywhere (probably because it was damp from the plastic). I might try Christmas lights also, especially if we have the temperatures we had last winter!

I'm hoping for better results this year!