How can I bring an outdoor fern indoors for the winter without causing it to much distress or loss of foliage?

First, if you're bringing it in you don't want to bring any pests with it. Take it to a "staging area" where there are no other houseplants so you can make sure it's "clean". I would use a houseplant insect killer on it or if you don't want to use poison spray it with neem oil or horticultural oil. If you use the oils spray them well, bottoms and tops of fronds. Let it sit in that "staging area " for a few days and then look it over carefully. Use a magnifying glass and see if you see anything moving. Some pests like spider mites are really small. Once you feel it has no pests bring it into your house.





Since there are different kinds of ferns with different needs put it where it is in conditions as close to where it was outdoors as possible. It won't need quite as much water inside. But if you have a gas furnace and no humidifier you may want to mist the foliage every few days.

How can I bring an outdoor fern indoors for the winter without causing it to much distress or loss of foliage?
Make sure you keep it by a window that has similar sunlight.