so my banana in my polytunnel are still slowly growing. even though its winter. there is less light and heat. I have a heater but I was hoping they would go dormant. I don't know whether to fertilise them or not? if I don't their growth ie leaves are significant undeveloped ie yellow/ white instead of green. I wouldn't mind but the growth isn't great. I know they are tropical but I don't know what to do.

any help is appreciated?

thanks