Boston fern (sword fern) care

Light

Boston fern wants the spot a few feet back from a sunny window — bright enough to read a paperback at noon, but the sun never falls directly on the leaves. Medium to bright indirect light. Direct sun scorches the fronds; deep shade thins the plant out. A faint hand shadow at midday is the right amount; a sharp dark shadow means it's getting direct sun and probably too much.

Watering

Water boston fern when the top 1 cm of soil is just dry, every 3-5 days. The actual day count varies with pot size, light, and season — the finger test (or lifting the pot to feel its weight) is more reliable than a fixed calendar. Empty any drainage saucer afterwards so the pot isn't sitting in water. Keep evenly moist with rainwater or filtered water — Boston ferns are sensitive to chlorine and minerals.

Soil and pot

Boston fern grows best in moisture-retentive houseplant compost. Peat-free compost with added coconut coir holds moisture without going soggy. A pot with a working drainage hole is non-negotiable for this species — even free-draining mix will turn soggy in a closed planter. If you love the look of a decorative pot without a hole, use it as a cachepot around an inner nursery pot you can lift out to water.

Humidity and temperature

Boston fern sits happiest at around 60-70% humidity and 15-24°C (60-75°F). High humidity is essential. Daily misting is not enough — use a humidifier. If you keep the room above 15 year-round and avoid placing the plant near a cold draught, a hot radiator, or an air-conditioning vent, you have already handled the two biggest indoor stressors.

Fertilising

Feed boston fern sparingly. Quarter-strength balanced feed every 4 weeks during the growing season; ferns are sensitive to over-feeding. Skip fertiliser entirely on a stressed, recently-repotted, or actively wilting plant — fertiliser salts make damage worse, not better. Wait for a round of healthy new growth before resuming a feeding rhythm.

Common problems

Below are the issues we see most often on boston fern in the Growli community. Where a problem matches one of our diagnostic guides, click through for the full step-by-step recovery plan written for boston fern specifically.

• Brown frond tips — Low humidity or tap-water minerals.
• Yellow fronds — Underwatering, sudden drying out, or too much direct sun.
• Massive frond shedding — Acclimation shock or a sudden change in humidity; trim back and improve conditions.
• Pale fronds — Insufficient light or under-feeding.

Companion plants

Boston fern pairs well with Calathea, Peace lily, and Spider plant. These are species with similar light and water needs, so you can group them in the same room or on the same shelf and water as a batch.

Propagation

Divide the rhizome at repotting; each division must have several healthy fronds and its own roots. Propagation is the cheapest, most satisfying way to expand a collection — and it doubles as insurance against losing a mature plant to an accident. Take a backup cutting once the parent is established and healthy.

Toxicity to pets

Boston fern is pet-safe. ASPCA lists Nephrolepis exaltata as non-toxic to cats and dogs. A safe lush option for pet households. If you keep cats, dogs, or curious children in the house, weigh placement carefully — a high shelf or a hanging planter is enough for casual safety. For severe ingestion incidents, call your local vet and the ASPCA Animal Poison Control Center (in the US, 888-426-4435).

Pet-safety status is sourced from the ASPCA Toxic and Non-Toxic Plant List, which catalogues the most-asked-about plants for cats, dogs, and horses.

Boston fern deep-dive guides

Every aspect of boston fern care, each with its own calibrated guide:

• Common boston fern problems & fixes
• Boston fern watering schedule
• Boston fern light requirements
• Best soil mix for boston fern
• Boston fern fertilizing guide
• When to repot boston fern
• How to propagate boston fern
• How to prune boston fern
• What's eating my boston fern?
• Boston fern growth rate & size
• Boston fern cold hardiness
• Boston fern temperature & humidity
• Is boston fern toxic to cats & dogs?
• Is boston fern toxic to cats?
• Is boston fern toxic to dogs?
• All 14 Nephrolepis varieties

Featured in these plant shortlists

Boston fern qualifies for 10 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

• Best pet-safe houseplants — Houseplants the ASPCA lists as non-toxic to cats and dogs — every one verified against the ASPCA toxic and non-toxic plant list.
• Best low-light houseplants — Houseplants that need no direct sun and cope with a north-facing room or a spot well back from a window.
• Best plants for a north-facing window — Houseplants for a north-facing window: bright, even, indirect light and no scorching direct sun. Each pick verified against its documented light needs.
• Best pet-safe low-light plants — Non-toxic to cats and dogs AND happy with no direct sun — the two hardest constraints to satisfy at once.
• Best humidity-loving houseplants — Houseplants that thrive in a bathroom, kitchen, or by a humidifier — selected by documented humidity preference.
• Best bathroom plants — Humidity-loving houseplants that also cope with lower light — suited to the steamy, often-dim conditions of a typical bathroom.
• Best pet-safe bathroom plants — Non-toxic to cats and dogs and happy in the humid, lower-light conditions of a bathroom — safe greenery for the smallest room.
• Best pet-safe bedroom plants — Non-toxic to cats and dogs and happy in lower light — calming greenery for a bedroom where a pet often sleeps too.
• Best cat-safe plants — Houseplants the ASPCA lists as non-toxic to cats (and dogs) — safe greenery for a home with a curious cat.
• Best dog-safe plants — Houseplants the ASPCA lists as non-toxic to dogs (and cats) — safe greenery for a home with a curious dog.
• Browse all 30 plant shortlists — pet-safe, low-light, drought-tolerant and more

Related guides

Boston fern is also commonly called sword fern or Boston sword fern.

• Boston fern yellow leaves — causes and the fix
• Boston fern curling leaves — causes and the fix
• Boston fern drooping — causes and the fix
• Boston fern brown spots — causes and the fix
• Boston fern no new growth — causes and the fix
• Boston fern vs Maidenhair fern — which to choose
• Boston fern vs Spider plant — which to choose
• Sarcochilus falcatus care — light, water and common problems
• Aerangis fastuosa care — light, water and common problems
• Aerangis rhodosticta care — light, water and common problems
• All 10153 plant care guides in the Growli library