Re: hardiness of musa thomsonii?
I tested some Musa thomsonii some years ago, I protected them like Musa basjoo, but they are not hardy despite of the basjoo winter protection.
Musa thomsonii is not suitable for climates with cold and frosty winters with continuous black frost periods with deep frozen ground, despite of USDA zone 8a in Hamburg. The duration of frost periods is important to tell about hardiness, not only the lowest winter temperatures! Otherwise you need to heat the winter protection with thermostat switched heating cables in the soil and at the corm!
With the best