Thanks!
The greenhouse was heated with a 20,000 BTU natural gas heater.
To germinate the seeds, I used the regular germination flats with the humidome. I used black magic germination mix and used germination heat mats (on 24/7). I had a ton of Ensete sprouts within 2-3 weeks and musa sprouts in 1-2 months.
To overwinter the basjoo, I wrapped the stalks in plastic, placed a wire cage around the stalks and filled it up with leaves. Then placed a large tarp over the whole thing to keep it dry. The stalks survived, but the offshoots easily outgrew the larger stalks. The plant died the next winter from rot.