I live in south central Indiana, zone 6 and I have been growing bananas for several years. Always tough for me to get them through the winter. I used to work with a woman that grew them here and she got fruit every summer. She would over winter them, dormant, in her basement like you would over winter cannas, just in a card board box leaning up against the wall. She said her basement was full of them every year. I haven't done well with this, mine seem to dry up and die but I keep trying. I have read that to over winter them in a dormant state they need to be at least 3 ft tall. That would go for the Basjoo, too. I have not heard that Blue Java is hardy although I have heard that Orinoco can be grown in zone 7 with a good mulch cover. That is the hardiest fruit bearing banana I have read about.