Boston Fern (Sword Fern) care

Light

Picture the indirect light an east-facing window gives mid-morning — that's the brightness boston fern grows fastest in. Thrives in bright to medium indirect light. Near a north or east-facing window is ideal; keep 1–2 m from a south or west window to avoid direct sun, which causes bleaching and browning. Tolerates lower light levels than many houseplants, but growth slows and fronds become sparse. You'll know it's right when new leaves come out the same size and colour as the established ones. Smaller, paler new leaves = move closer to the window.

Watering

Aim for every 3–4 days in spring and summer; every 5–7 days in winter for boston fern, but treat that as a starting point rather than a rule. A south-facing summer windowsill will dry the pot twice as fast as a north-facing winter room. Lift the pot; if it feels noticeably lighter than it did wet, water it. Soil should be kept consistently moist but not waterlogged. Boston ferns are relatively drought-tolerant compared to maidenhairs, but prolonged dryness causes frond drop and browning. Use room-temperature water and ensure the pot drains freely. Reduce watering frequency in winter.

Soil and pot

Boston Fern grows best in well-draining, humus-rich potting mix. A standard quality peat-free compost mixed with perlite (3:1) provides good drainage while retaining adequate moisture. A slightly acidic pH of 6.0–6.5 is preferred. Repot every 1–2 years in spring when roots begin to protrude from drainage holes. 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 50–70% humidity and 13–24°C (55–75°F). Requires moderate to high humidity to prevent frond tip browning. Pebble trays with water, regular misting (targeting the air around the plant rather than the fronds), or a humidifier are effective. Particularly prone to drying in centrally heated rooms in winter. If you keep the room above 13–24°C 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. Feed every 4 weeks from April to September with a balanced liquid fertiliser at half strength. Avoid over-feeding, which causes fertiliser salt build-up and brown frond tips. Do not feed from October to March. Flush the pot with clean water periodically to clear salt accumulation. 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. Each is annotated with the most common cause so you know where to start.

• Frond tip browning — The most common Boston fern complaint, caused by low humidity, inconsistent watering, fluoride in tap water, or proximity to heat sources. Switch to filtered or rain water, raise humidity above 50%, water consistently, and relocate away from vents and radiators.
• Frond drop and shedding — Boston ferns shed fronds readily when stressed by cold draughts, sudden temperature changes, or being moved. Maintain stable temperatures above 13°C, avoid draughty windowsills, and minimise repositioning the plant. Shed fronds will be replaced by new growth from the crown.
• Scale insects and mealybugs — Sap-sucking pests can colonise frond bases and stems, causing yellowing and sticky residue (honeydew). Remove manually with a damp cloth or cotton pad dipped in isopropyl alcohol, and treat with insecticidal soap spray. Check new plants at purchase.

Propagation

Propagate by division of established clumps in spring, ensuring each section has healthy crown tissue and roots. Also propagated via runners (stolons) that can be pegged into moist compost while still attached to the parent, severed once rooted. Not grown from spores commercially. 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. Nephrolepis exaltata and its cultivars, including 'Bostoniensis', are listed by the ASPCA as non-toxic to dogs and cats. This is one of the most reliably pet-safe popular ferns. 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:

• 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
• 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?

Featured in these plant shortlists

Boston Fern qualifies for 15 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 drought-tolerant houseplants — Houseplants that prefer to dry out — forgiving of forgotten watering and ideal for travel or busy weeks.
• Best trailing & climbing houseplants — Vining and trailing houseplants for shelves, hanging pots, and moss poles — selected by growth habit.
• Best houseplants for beginners — Forgiving of irregular light and watering — the houseplants least likely to die in a new plant parent’s first season.
• 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 trailing & hanging plants — Trailing and climbing plants the ASPCA lists as non-toxic to cats and dogs — safe for shelves and hanging pots in a pet home.
• Best pet-safe low-maintenance plants — Non-toxic to cats and dogs and forgiving of forgotten watering — the easiest safe choices for a busy pet household.
• 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 29 plant shortlists — pet-safe, low-light, drought-tolerant and more

Related guides

Boston Fern is also known as Boston Fern, Sword Fern, and Ladder Fern.

• ZZ Plant Lucky care — light, water and common problems
• Dracaena Fragrans Massangeana care — light, water and common problems
• Dracaena Deremensis Warneckii care — light, water and common problems
• All 6887 plant care guides in the Growli library