Looks like (at least on my computer) the site didn t post my long boring reply to your thread, so I ll try again, with a quick boring reply.
Your banana looks like a dwarf cavendish not a basjoo, so you may simply want to bring it indoors at night if the temperature is too cool. Here in NJ it was 41 last night and my bananas were completely fine. Your plant is small enough to grow indoors by a sunny, south facing window, providing you are very careful not to over water it. Outdoors in the heat it should be ok with lots of water. Best with full sun early in the day, and partial shade in the very hot afternoons, if you can find a good spot.
Don t repot it until it is much bigger, I have a 5 basjoo in a similar size pot which is doing well. I don t yet have any experience planting them in the ground.
My largest banana is a giant cavendish (I think) which I got from Key West as a 1" pup attached to a dying mother. That pup is now (less than a year later) 6 tall with a pseudostem so thick I can t get both hands around it. Huge 48" by 24" leaves!
Anyhow I apologise if you can see both posts of mine and I repeat myself.
Good luck,
~Joe