True ferns send fronds up from the center of the plant. The new fronds, known as fiddleheads, are tightly coiled as they emerge. Outdoors, old fronds turn brown in the winter and you need to remove them each year. Fronds on houseplant ferns live longer, but you'll still need to neaten the plants occasionally. The exception is leathery-leaved staghorn fern (Platycerias spp.), which rarely needs any pruning.
For shady, moist places and woodland gardens, ferns contribute a layer of low-care greenery that conveys a feeling of serenity. Once the ferns are established, cut old fern fronds back in late winter or early spring before the new fronds unfurl. Use a sharp pair of pruning shears dipped in rubbing alcohol before and after use and between cuts. Cut the old fronds off just above soil level, taking care not to cut into the central crown from which new growth emerges. Time the pruning so old fern leaves lend presence to the landscape in winter but don't obscure the new spring growth.
Growing Season Pruning
If some species of garden fern develop unattractive fronds during the growing season, or if they wither from extended drought, cut them back as you would for winter pruning. Cover the crown with leaves and either wait for rain or water the plant so new growth emerges. Use this technique with lady fern (Athyrium filix-femina), which grows in U.S. Department of Agriculture plant hardiness zones 3 through 9 and for Northern maidenhair fern (Adiantum pedatum), which grows in USDA zones 4 through 9.
Fronds tend to stay green on ferns kept as houseplants such as Boston fern (Nephrolepis exaltata), which also grows outdoors in USDA zones 10 through 12. Keep the relative humidity high, and Boston fern can retain its fronds and produce offsets, reaching a large size. If relative humidity is low, especially during winter or the soil becomes dry, the fronds can develop brown ends and shed. To regenerate ferns with dried fronds, cut all the fronds off within 2 inches of the soil using sharp, disinfected pruning shears. If you grow frost-tender ferns in containers outdoors during the summer, prepare them for their time indoors in winter in limited spaces by cutting the lower fronds even with the pot rim and the center fronds down to 10 inches.
Growing differently from other types of ferns, staghorn fern has leathery fronds and grows as an epiphyte on rocks and trees in the wild. It doesn't need soil, but grows mounted to a piece of bark with the roots surrounded by sphagnum moss. Staghorn fern doesn't need cutting back. Remove only damaged or diseased frond portions when you see them, trimming them away with sharp scissors dipped in rubbing alcohol. Never prune or remove the oval rounded fronds at the base of the plant. Common staghorn fern (Platycerium bifurcatum) grows outdoors in USDA zones 9 through 12.