Houseplant · Nephrolepidaceae
Boston Fern
Nephrolepis exaltata
Fed steady moisture and humid air, the Boston fern arches out in long, feathery fronds of soft green.
Bright indirect
61–70°F · 16–21°C
USDA 10–12
2–3 ft · 0.6–0.9 m
Overview
The Boston fern wears its name in its shape: long fronds that arch up and then bow back down over the rim of a pot, each one a slender green blade lined with rows of small leaflets. It belongs to the genus Nephrolepis, a tribe of humid tropical forests, and that origin shows in fronds that stay soft and pliant in warm, damp air. In bright light out of direct sun it grows fast, the new fronds uncurling from the center to thicken the whole plant into a feathery green mound.
Touch tells the story of its health. Held in steady moisture and high humidity, the leaflets stay supple and a clean, even green, the two conditions ordinary indoor air rarely offers. Let the soil dry or set it by a heater and the change is visible at once, the tips going brown and brittle and the small leaflets dropping away. Kept evenly moist in humid air, the fronds hold their color and their fine, feathered edge.
Up close the plant reads as nothing but soft greenery, and the ASPCA lists it as non-toxic, so there is no hidden sting in those tender leaflets. That makes it a rare houseplant whose fronds can be touched, brushed, or even nibbled without harm.
Care
The short version: the fern wants bright indirect light, soil kept evenly moist but never soggy, and humid air around 61°F to 70°F (16°C to 21°C). Feed it monthly through the growing season and divide the clump every few years.
Light
The fern colors best in bright, indirect light, the glow beside a window rather than sun falling straight on the leaflets. It also greens up in medium light, partial shade, and even full shade, so a dim corner keeps it alive, while direct sun bleaches and scorches the soft fronds.
Water
Held in evenly moist but never soggy soil, the leaflets stay supple and green, with only a slight easing back in winter. A dry-out shows fast on the plant, the tips browning and the small leaflets dropping, so even watering does more for the look of the fronds than anything else.
Soil
A peaty, soil-based mix that drains freely yet holds water, such as a peat and vermiculite blend, keeps the fine roots damp. That steady moisture at the root feeds the soft, pliant texture the fronds carry above.
Temperature
The fronds stay freshest between 61°F and 70°F (16°C to 21°C), ordinary room warmth. Cold drafts and the dry heat of a radiator pull moisture from the thin leaflets and leave them crisp at the edges.
Humidity
This is a high-humidity plant, and dry air shows on it first, drying the delicate leaflet tips. Double potting or a tray of wet pebbles under the pot lifts the moisture around the fronds far better than a quick mist over their surface.
Feeding
Fed monthly from spring to early fall while new fronds unfurl, the plant rests through winter. A weak, half-strength liquid feed or a slow-release houseplant fertilizer keeps the color even, since a strong dose scorches the fine roots that draw it up.
Pruning
Old or browned fronds are cut at the soil line to clear the crown for fresh growth. A plant dried to brittle stubble pushes new green fronds from the base once its old fronds are cut back to about 2 inches.
Repotting
The clump is divided every few years in spring, once the fronds crowd the pot. Roots circling the container and tightly packed fronds losing their vigor are the visible cue that the plant has outgrown its space.
Size & spacing
Indoors the fern reaches about 2 to 3 feet (61 to 91 cm) tall and just as wide, the long fronds arching out on every side. They hang at their fullest where they can spill freely, as from a basket or the edge of a high stand.
Troubleshooting
Almost every Boston fern problem reads on the fronds themselves, where dry air, dry soil, or a pest leaves its mark in color and texture. Brown tips, a sticky shine, or a dusting of white tell you what is wrong before the plant sheds in earnest. Match what you see on the leaflets below, then act while the green can still recover.
Fronds browning to a crisp as leaflets fall away
The soft green of the fronds turning dry and brittle points to dry air and dry soil, and the color fails first at the very tips of the small leaflets before they loosen and fall. Even moisture in the mix, more humidity from a pebble tray or double potting, and a place away from radiators and drafts let the green return. A fern dried to brown stubble grows back when its fronds are cut down to about 2 inches, the fresh growth pushing up bright and soft from the crown.
Fix:
- Keep the potting medium evenly moist but not saturated
- Raise humidity by double potting or setting the pot on a tray of wet pebbles
- If badly dried out, cut fronds back to about 2 inches to regenerate
Fronds glossed with stickiness and dotted with cottony white
Raised brown bumps and little tufts of white cotton clinging along the fronds and stems are scale insects or mealybugs, and the wet shine they leave on the leaflets is honeydew. The fronds worst crusted with them are cut away and binned, then the foliage left behind is treated. A close look over each new plant before it joins the others, and a stretch of isolation for an affected fern, keep the white specks from spreading.
Fix:
- Remove and discard heavily infested fronds
- Treat remaining foliage for scale or mealybugs
Toxicity
Those soft green leaflets carry no hidden danger. The ASPCA lists the fern as non-toxic to cats and dogs, and no toxic compound has been reported in the plant, so the fronds stay safe within reach of curious animals and children.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
The ASPCA lists Boston fern as non-toxic to cats with no toxic principle on record, so a cat that bites into a soft green leaflet comes to no harm.
Dogs None
Dogs are safe as well. The ASPCA names the fern non-toxic to them, and a frond chewed to shreds will not poison the dog.
Horses Safe
No toxic compound is recorded in the plant, so a horse that tears off a frond and chews the fine leaflets runs no poisoning risk.
Rabbits Safe
A rabbit can nibble the slender leaflets without harm, since the fern holds nothing toxic. A spread of other greens still makes a better staple than fern fronds.
Livestock Safe
Cattle, goats, and sheep meet no toxic principle in the plant, so a mouthful of fronds from a stray fern is safe.
Birds Safe
The thin green fronds hold no known toxin, which makes this fern safe to keep near birds.
People Safe
The fern is harmless to people, so a child who mouths a leaflet is fine. It is not grown as food, though, so no part of the plant is meant to be eaten.
Varieties
A handful of named cultivars turn up most often, set apart by the size of the plant, the cut of the leaflets, and the color of the new fronds. These are the ones worth knowing by sight.
'Bostoniensis'
The classic Boston fern, sending up long, arching fronds that stretch to about 4 feet long and 6 inches wide, each lined with small green leaflets.
'Compacta'
A shorter, denser form of the standard fern, its fronds drawn in tighter on a smaller frame.
'Florida Ruffle'
Its fronds carry denser, more finely divided leaflets that pile into a soft, ruffled texture.
'Rita's Gold'
Its new fronds emerge in a luminous chartreuse to golden-green before the color settles.
How to propagate
Boston ferns make more of themselves readily, the dense clump splitting cleanly and thin runners striking root on their own to raise fresh fronds.
DivisionEasy
Spring · A few weeks to a couple of months to root and resume growth
Dividing the dense clump is the most practical way to make more. In spring the root ball is sliced straight down into halves or quarters, each piece keeping as many fronds as it can, and the divisions then take a few weeks to a couple of months to root and push new fronds. The fern also creeps outward on thin runners that strike root wherever they press into the soil, and in the wild it grows from spores set in rows on the undersides of the fronds.
Offsets & pupsEasy
Spring to summer · Several weeks once a rooted runner is separated
The fern trails out wiry runners that bud small plantlets wherever they settle onto moist soil. Once one of these runners has struck root, it is cut from the parent in spring or summer, and the young plant fills in over a few weeks.
Myths
Boston fern is poisonous to cats and dogs like so many houseplants.
The plant is safe. The ASPCA lists Boston fern as non-toxic to both cats and dogs, so its soft green fronds can grow in homes where many other houseplants cannot.
Misting is the best way to give a Boston fern the humidity it craves.
Misting adds little humidity and only beads the fronds with water, and that lingering wet on the leaflets invites foliar leaf spot. Double potting or a pebble tray raises humidity far more reliably, leaving the leaflets dry and the green clean.