I grow some phenomial size ferns from June through Oct. outside. They generally double or triple in size. I live in the woods and have found the right spot for light and shade. In a week or so, we will have frost and I have to bring them inside. As good conditions for growth outside, indoors is bad. Electric heat, low humidity and either too much (French doors) or not enough light. I don't overwater and fertilize once or twice a winter. My kill rate is 80 percent and those that make never thrive the next summer. Ideas? Thanks.