Most ferns are woodland or wetland plants that thrive in shady, moist places. When they're invited indoors, allowances must be made for their exotic needs. Central heating and air conditioning removes the humidity that ferns need in their native settings. Compensate for these disparities by assessing your fern’s needs and designing its home so that it can adapt gradually--and successfully--to indoor life indoors.
Plant or re-pot your fern in a well-drained container. Drill extra holes in a clay pot or use a moss basket to allow air to circulate freely through the roots. Fill the container with a soilless potting mixture for ferns, or make your own using equal parts of well-rotted compost, humus and peat moss; the result is as close as you’ll get to a forest floor. Staghorn ferns are the exception; they are grown in sphagnum moss on a piece of tree or cork.
Put the fern in a place where the temperature is right. Brake ferns need nighttime temperatures of 50 to 55 degrees F and daytime temperatures of 68 to 70 degrees F. Some tropicals, however, may want warmer temperatures. Consider that the temperature near a window may be too warm during summer for daytime and too cold during winter for nighttime temperatures. Set a thermometer next to the fern to check its environment before placing it permanently.
Establish and maintain a humidity regimen. Water and mist with tepid water; your soil is very porous and ferns don’t like wet feet, so resolve to water when soil begins to dry. Put the fern on a tray filled with 2 inches of pebbles and 1 1/2 inches of water to provide better humidity levels. Set sphagnum baskets and staghorn plaques in a soap-free basin of tepid water to re-hydrate both container and soil.
Feed ferns half-strength houseplant fertilizer monthly from spring to early fall. Their primary need is nitrogen to grow. They should not need fertilizer from October to March, unless they are actively growing.
Groom ferns regularly. Remove fading foliage and check for honeydew (a sign of fern scales), mealybugs or other pests. Check tops and bottoms of leaflets, and if you find pests, isolate the plant and apply an insecticide that is marked as safe or designed for ferns.