Boston ferns can be kept outside if the temperature is above 50 degrees Fahrenheit, according to About.com. Boston ferns can survive a brief dip in temperature below 50 degrees, but they do best in humid conditions when the temperature is between 60 and 75 degrees.
According to Hionis Greenhouses, Boston ferns should be brought inside during colder seasons and stored in a basement to protect them from the freezing temperatures. About.com explains that, during the winter, watering can be reduced, and the plants should be kept away from air vents.
Boston ferns originate from tropical regions and often cover rainforest floors. They spread quickly and serve well as fill-ins and backdrops for landscapes.