Why is my Boston Fern Dying?

I have a fern that is being kept inside for the winter, it has been dropping leaves for a long time. The stems go black/brown and the tips die. The leaflets go yellow then brown and fall. I know what type of conditions they like but it is still dying. I have been misting it and I make sure its watered often. I also use grow lights sometimes on cloudier days. I have put it in a cooler spot in the house so I don't understand what else is wrong. SHould I be fertilizing it in the winter?