Boston fern is a cultivar of Nephrolepis exaltata, or sword fern, which is native throughout Florida. The stiff 3- to 4-foot upright fronds of sword fern were commonly found in Victorian-era parlors. The more gracefully arching fronds of Boston fern, Bostoniensis, were discovered by chance among a shipment of sword ferns sent to a Massachusetts florist in 1894, and quickly became popular.
The Boston fern is tender (as opposed to the hardy fern, which survives as a perennial in cold climates). Often grown in hanging baskets, it is a fixture of summer porches and makes a lovely houseplant as well.
Provide Boston fern with a potting soil that is well-drained but has the ability to hold water so that the plant does not dry out too quickly. Soilless potting mixtures work well.
If keeping a Boston fern outdoors for the summer, find a spot with mostly shade or some filtered sun. When Boston ferns are kept indoors, they require a sunny location. Be sure the center of the plant is getting enough light, otherwise the plant will lose its shape.
Boston ferns need humidity to look their best, especially when kept indoors. You can provide extra moisture by keeping the fern on a tray of pebbles filled with water or by misting it frequently with lukewarm water.
Water enough to keep the soil slightly damp during the Boston fern's active growing season; keep it somewhat drier over the winter. As new fronds begin to appear in response to longer days in late winter, begin providing a little more water.
Trim the plant regularly to keep it looking neat. Remove any broken or brown fronds at the level of the soil.
Feed Boston fern with an all-purpose plant food once a month during the spring and summer. Ferns do not require much fertilizing.
Provide moderate indoor temperatures. According to Master Gardener Fred Davis, a very recent study showed that Boston ferns kept at even day and night temperature of about 72 degrees Fahrenheit grew much better than those exposed to widely fluctuating temperatures.
If your Boston fern has been summering outside, trim it well before bringing it inside to minimize clean up. Boston ferns tend to shed a lot of fronds when adjusting to a new environment. Remove the older, drooping fronds, leaving the young, upward-facing fronds.
Propagate your fern through the stolons if desired. Stolons are the thin runners that sprout from the sides of the fern. When the stolons come in contact with soil, they will root and form a new plant. If no new plants are desired, simply trim the stolons away.
Divide an adult Boston fern in late winter every couple of years to keep it healthy and vigorous. Split the root ball down the middle with a sharp knife and trim away all but the youngest fronds to soil level when dividing. It is best to divide the fern rather than provide a bigger container, since the plant will eventually become too big to handle.