I have my bananas in a bed of their own, I dump lots of organic matter in there and sprinkle fertilizer about once a month in the summer. Because it is so hot and humid here, the organic stuff (clippings and such) breaks down really quickly. I also try and keep it damp in the dry season, winter, but they grow a lot more in the rainy season. I don't think you can give them too much water or too much compost, not sure about the fert. If you are leaving them out in the winter, I'm guessing they are hardy, then piling lots of leaves and clippings on them would be good as it would break down over the winter and be compost by spring. Most people here use the banana bed as a compost bed, they throw all the green stuff from the kitchen and the garden in there, they like egg shells and coffee grounds as well. I run the hose and flood them every week in the dry season, they get the monsoon rains in the summer. Because they need so much water, they lose a lot of nutrients. Think of them as big grass, heavy feeders.
