Boston Fern

How to care for Boston Fern

Light

Boston Ferns thrive in bright, indirect light, such as the light found near a north- or east-facing window. Direct sunlight will scorch the fronds and cause them to yellow, while excessively dim conditions slow growth and produce sparse, pale foliage. A few metres back from a bright south- or west-facing window, behind a sheer curtain, is also suitable.

Watering

The compost should be kept consistently and evenly moist throughout the growing season from spring to autumn. Water thoroughly when the top centimetre of compost begins to feel dry, allowing excess to drain freely. In winter, reduce watering slightly but never allow the root ball to dry out completely. Use room-temperature water, and avoid using heavily softened or fluoride-treated tap water where possible, as this can cause tip burn.

Soil and potting

A peat-free, moisture-retentive compost with good drainage is ideal. A mix of coir, perlite, and finely composted bark in roughly equal parts works well. Avoid heavy, compacting media that hold stagnant moisture around the roots. A slightly acidic pH of 5.5 to 6.5 suits the plant.

Feeding

Apply a balanced, diluted liquid fertiliser at half the recommended strength once a month during spring and summer. Avoid high-nitrogen feeds that encourage lush but weak growth. Do not feed during autumn and winter when growth naturally slows. Over-feeding can cause salt build-up in the compost, which damages roots.

Humidity and temperature

High humidity is essential; levels below 40% cause rapid browning of frond tips and edges. Mist the fronds regularly, stand the pot on a tray of damp pebbles, or use a humidifier nearby. Avoid placing the plant near radiators, open fires, or air-conditioning vents. The preferred temperature range is 15 to 24 degrees C, and the plant should not be exposed to temperatures below 10 degrees C or sudden cold draughts.

Repotting

Repot every one to two years in spring, moving up one pot size when roots begin to emerge from drainage holes or the plant dries out very rapidly after watering. Choose a pot that is only slightly larger than the root ball, as too large a container holds excess moisture and may promote root rot. Terracotta pots can help regulate moisture but may require more frequent watering than plastic equivalents.

Pruning

Remove dead, brown, or damaged fronds by cutting them cleanly at the base with sharp, clean scissors or secateurs. Regular removal of old fronds encourages fresh growth and keeps the plant tidy. Lightly trimming the tips of fronds is possible but rarely improves appearance, as the cut ends remain visible. In spring, cutting back a heavily congested or struggling plant quite hard can promote a flush of healthy new growth.

Is Boston Fern toxic?

Common problems

How to propagate

Division

At repotting time in spring, carefully separate the root mass into two or more sections, each with healthy fronds and roots attached. Pot each division into its own container with fresh, moist compost and keep in a warm, humid position until established.

Runners (stolons)

Nephrolepis exaltata produces wiry, thread-like stolons that creep from the parent plant. Pin the tip of a stolon into a small pot of moist compost placed alongside the parent plant; once the plantlet has rooted and produced new fronds, sever the stolon from the parent.

Spores

Collect the brown spore cases from the undersides of mature fronds and sow the spores on the surface of moist, sterile compost in a covered propagator. Germination is slow and irregular, often taking several weeks to months, and requires consistently warm, humid conditions throughout.

Where Boston Fern comes from

Native to Arizona, Bahamas, Bermuda, Bolivia, Brazil North, Brazil Northeast, Brazil South, Brazil Southeast, Colombia, Costa Rica, Cuba, Ecuador, Florida, Hawaii, Honduras, Jamaica, Leeward Is., Louisiana, Mexico Gulf, Nicaragua, Panamá, Puerto Rico, Texas, Turks-Caicos Is.. Now naturalised or cultivated in 14 other regions worldwide.

Story and origins

The genus name Nephrolepis derives from the Greek words 'nephros', meaning kidney, and 'lepis', meaning scale, referring to the kidney-shaped or reniform indusia that cover the spore cases (sori) on the undersides of fertile fronds. The species epithet 'exaltata' comes from the Latin 'exaltatus', meaning raised up or tall, describing the plant's characteristically erect and arching fronds. The common name 'Boston Fern' commemorates the city of Boston, Massachusetts, where the popular cultivar 'Bostoniensis' was first identified in the late nineteenth century.

Nephrolepis exaltata is native to a wide range of tropical and subtropical regions, including Florida, the Caribbean, Central and South America, Africa, and Polynesia, where it grows in humid forests, swamps, and disturbed ground. It was known to botanists from early European explorations of the tropics, but its rise to prominence as a houseplant began with the discovery of the cultivar 'Bostoniensis' in 1894, which spread rapidly through the nursery trade in the United States and Britain. During the late Victorian and Edwardian periods, large specimen ferns were fashionable parlour plants, and Boston Ferns were displayed in elaborate ornamental stands. They fell from favour in the mid-twentieth century but experienced a significant resurgence in popularity during the houseplant boom of the 1970s and again in the 2010s. In some Caribbean and Central American traditions, ferns including Nephrolepis species have been used in folk medicine, though these uses are not scientifically validated.

Varieties to know

Nephrolepis exaltata 'Bostoniensis'

The classic cultivar from which the common name derives; selected in Boston in 1894 for its broad, arching fronds and vigorous growth

Nephrolepis exaltata 'Fluffy Ruffles'

Compact cultivar with densely frilled, ruffled pinnae that give the fronds a full, textured appearance

Nephrolepis exaltata 'Tiger'

Notable for variegated, yellow-striped fronds; less vigorous than the species but visually distinctive

Nephrolepis exaltata 'Smithii'

Dense, compact form with very finely divided pinnae, often described as lacy or feathery in texture

Nephrolepis exaltata 'Rooseveltii'

An older cultivar with wavy, slightly ruffled pinnae; considered more tolerant of variable conditions than some other selections

Fun facts

• Boston Ferns are effective air purifiers; a 1989 NASA Clean Air Study identified Nephrolepis exaltata as one of the most efficient houseplants for removing formaldehyde and xylene from indoor air.
• The cultivar 'Bostoniensis' was discovered by chance in a shipment of Nephrolepis exaltata sent to a Boston florist, Frederick C. Becker, in 1894, and rapidly became a horticultural sensation in North America.
• Boston Ferns can live for many decades under suitable conditions; specimens over 50 years old have been recorded in botanical collections.
• The plant reproduces naturally via both spores and vegetative stolons, allowing a single individual to colonise a large area in its native tropical habitat.
• In the Victorian era, large Boston Ferns displayed on plant stands known as ferneries were considered status symbols in middle-class drawing rooms on both sides of the Atlantic.

Boston Fern FAQ