How often should I water in the winter?

It was a beautiful sunny Christmas day so I spent some time out in the greenhouse. It’s pretty dry where these two bananas are planted. The Pisang Ceylon doesn’t have a mark on it. The Basjoo on the other hand has seen better days. I want to hydrate them but not cause any rot. Would half a gallon be ok do you think?

Dwarf Cavendish not planted in ground but will need a good watering soon. Still growing very slowly