The Temperature Range for an Outside Boston Fern

Boston ferns were used as houseplants in the 19th century, but the native habitat of the fern is in swamps and forests of Florida. Boston ferns also are found in Mexico, Africa, Polynesia, and Central and South America.



Boston ferns (Bostoniensis) have arching fronds that grow up to 3 feet long and 3 inches wide. The dark green fronds start off wide at the bottom and come to a point at the tips.


U.D. Department of Agriculture hardiness zones for the Boston fern are 9, 10 and 11, all of which have average low temperatures of 20 to 40 degrees Fahrenheit. Ideally, the temperature for outdoor ferns is between 65 and 95 degrees Fahrenheit, but the Boston fern will tolerate much colder temperatures.

Temperature Effects

Boston ferns grown in the ground outdoors will die back at first frost and grow back in the spring. Ferns grown in containers outdoors will remain green until the temperatures drop to the 40s. Once the temperatures drop, the green frond will turn yellow over the winter.