Boston Fern
Nephrolepis exaltata
The Boston Fern (Nephrolepis exaltata) is one of the most widely recognized and cultivated ferns in the world, beloved for its gracefully arching fronds covered in delicate, bright green leaflets that create a lush, fountain-like display. First discovered as a mutant in a shipment of sword ferns from Philadelphia to Boston in 1894, this natural variant with its elegantly drooping fronds became an instant sensation during the Victorian fern craze and has remained one of the most popular houseplants and hanging basket plants ever since.
• One of the most popular houseplants in the world for over 125 years
• Originated as a natural mutation discovered in Boston, Massachusetts in 1894
• A variant of the wild Sword Fern (Nephrolepis exaltata) with gracefully arching rather than upright fronds
• Exceptionally efficient at removing indoor air pollutants, particularly formaldehyde
• The Victorians were so obsessed with ferns that the era was called the "pteridomania" (fern craze) period
Taxonomy
• Native range extends from Florida and Mexico through Central America, the Caribbean, and tropical South America
• Also native to tropical Africa, Southeast Asia, Polynesia, and Australia
• Found in humid forests, swamps, and shaded ravines from sea level to approximately 1,300 m
• The species grows as both a terrestrial and epiphytic fern in its native habitats
• The original wild form (var. exaltata) has upright, stiff fronds and is known as the Sword Fern
• The "Boston" form (var. bostoniensis) was discovered in 1894 in a nursery in Boston, Massachusetts, as a chance mutation in a shipment of sword ferns from Philadelphia
• Named by the American nurseryman C. D. Fosdick
• Hundreds of cultivars have been developed from the original Boston mutation, varying in frond length, width, and degree of ruffling
• Now naturalized in many tropical and subtropical areas worldwide where it has escaped cultivation
Rhizomes:
• Short, erect to creeping, scaly, producing numerous fronds
• Produces slender, wiry stolons (runners) that spread horizontally, rooting at the tips to form new plants
• Stolons allow the fern to form large, spreading clumps
Fronds:
• The most distinctive feature: long, arching to pendant, pinnate fronds 60-120 cm long and 10-15 cm wide
• The "Boston" form has gracefully drooping fronds, unlike the erect fronds of the wild sword fern
• Each frond consists of a central rachis (midrib) with 30-60 pairs of pinnae (leaflets)
• Pinnae are linear-lanceolate, 3-7 cm long and 5-10 mm wide, bright green
• Pinnae margins are slightly serrate (toothed)
• Fronds emerge as tight spirals (fiddleheads) and unfurl in a distinctive circinate vernation
• Stipe (leaf stalk): 5-15 cm long, scaly at the base, green to straw-colored
Sori (spore clusters):
• Small, round, brown, arranged in a row along the underside of each pinna near the margin
• Protected by a kidney-shaped indusium (protective covering)
• Produce thousands of microscopic spores
Growth Habit:
• Forms dense, fountain-shaped clumps of arching fronds
• Mature plants can span 60-90 cm in diameter
• The arching habit makes it ideal for hanging baskets
• Occurs naturally in forest understories, shaded ravines, swamps, and along stream banks
• Can grow terrestrially in soil or epiphytically on tree trunks and rocks
• Requires consistently high humidity for healthy frond development
• Spores are wind-dispersed and germinate on moist, shaded substrates
• The gametophyte (sexual) generation is tiny, heart-shaped, and requires a film of water for fertilization
• Spreads vegetatively through stolons, allowing rapid colonization of suitable habitats
• In the wild, the species is highly adaptable and can be found in both wet and seasonally dry forests
• Boston Fern has become naturalized in many tropical areas where it can be invasive
• Fronds provide habitat for numerous small invertebrates and amphibians in wild populations
• Serves as a pioneer species in disturbed, moist habitats
• Prefers bright, indirect light or medium filtered light; tolerates shade but growth is slower
• Avoid direct sunlight, which scorches the fronds
• Ideal temperature range: 16-24°C; prefers cool to moderate temperatures
• Requires high humidity (50-80%); essential for preventing brown frond tips
• Increase humidity with regular misting, pebble trays, or humidifiers
• Water thoroughly when the top 2 cm of soil feels dry; never let the soil dry out completely
• Use a well-draining, peat-based potting mix
• Feed monthly during spring and summer with a diluted balanced liquid fertilizer
• Trim brown or yellowing fronds at the base to maintain appearance
• Propagation by division of clumps or by rooting stolons (runners)
• Repot every 1-2 years when root-bound
• Susceptible to scale insects, mealybugs, and spider mites
• One of the best plants for removing formaldehyde and other indoor air pollutants
• Can be moved outdoors in shade during warm months
Fun Fact
NASA's famous Clean Air Study in 1989 found that the Boston Fern is one of the most effective plants at removing formaldehyde from indoor air, capable of removing approximately 1,863 micrograms of formaldehyde per hour — making it literally the houseplant equivalent of an air purifier. The original "Boston" mutant was so valuable that nurseries paid enormous sums for the first specimens, and its genetics spread through the horticultural trade like wildfire, producing over 100 named cultivars within just a few decades.
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