Fishtail Sword Fern (Fishtail Fern) care

Light

Fishtail Sword 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. Best in bright to medium indirect light. Tolerates some direct morning sun but burns in strong afternoon sunlight. An east-facing windowsill or a shaded spot on a bright patio is ideal. Too little light results in sparse, small fronds and weak, etiolated growth. 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 fishtail sword fern every 3–5 days in warm weather; every 6–8 days in cooler months. 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 the growing medium evenly moist throughout the growing season. Nephrolepis falcata is somewhat more drought-tolerant than delicate maidenhair ferns but benefits from regular, consistent watering. Allow only the top 2 cm of soil to dry before watering again. Ensure drainage holes are clear.

Soil and pot

Fishtail Sword Fern grows best in well-draining, moisture-retentive potting mix. A mix of peat-free compost and perlite (3:1) provides good structure. The fishtail sword fern adapts to slightly sandier mixes than some other Nephrolepis species. Slightly acidic to neutral pH (6.0–7.0) is appropriate. Repot every 1–2 years as roots fill the container. 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

Fishtail Sword Fern sits happiest at around 50–70% humidity and 18–30°C (64–86°F). Prefers moderate to high humidity, especially indoors in heated environments. Pebble trays, plant groupings, or a cool-mist humidifier help maintain suitable levels. In tropical outdoor conditions, ambient humidity is generally sufficient. Low humidity leads to brown frond margins. If you keep the room above 18–30°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 fishtail sword fern sparingly. Apply a balanced liquid fertiliser at half strength every 4 weeks during spring and summer. Avoid heavy feeding, which can cause soft, susceptible growth and brown leaf tips from salt accumulation. Do not fertilise in autumn or winter when growth naturally slows. 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 fishtail sword fern in the Growli community. Each is annotated with the most common cause so you know where to start.

• Loss of forked pinnae character — Under low-light or nutrient-poor conditions, new fronds may produce less pronounced forking and appear closer to a standard sword fern. Ensure adequate bright indirect light, feed regularly during growth, and the distinctive fishtail form will reassert itself on new fronds.
• Brown frond margins — Caused by low humidity, drought stress, or dry indoor air. Raise ambient humidity above 50%, water before the compost dries out, and move away from heat sources. Trim brown margins for aesthetics; affected areas will not recover but new fronds will be healthy.
• Root rot from overwatering — Soggy, poorly drained soil causes roots to rot, resulting in yellowing lower fronds and a decline in overall plant vigour. Check that the pot has adequate drainage holes, use a free-draining mix, and allow the soil surface to begin to dry before rewatering.

Propagation

Propagate by division of established clumps in spring, separating sections with healthy rhizome and fronds. Stolons can be pinned to moist compost while still attached to the parent plant and severed once rooted. Spore propagation is possible but requires controlled humid conditions and is slow. 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

Fishtail Sword Fern is pet-safe. Nephrolepis falcata belongs to the Nephrolepis genus, which is listed by the ASPCA as non-toxic to dogs and cats. No toxic compounds have been identified in this species. 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.

Fishtail Sword Fern deep-dive guides

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

• Fishtail Sword Fern watering schedule
• Fishtail Sword Fern light requirements
• Best soil mix for fishtail sword fern
• Fishtail Sword Fern fertilizing guide
• When to repot fishtail sword fern
• How to propagate fishtail sword fern
• Fishtail Sword Fern growth rate & size
• Fishtail Sword Fern cold hardiness
• Fishtail Sword Fern temperature & humidity
• Is fishtail sword fern toxic to cats & dogs?
• Is fishtail sword fern toxic to cats?
• Is fishtail sword fern toxic to dogs?

Featured in these plant shortlists

Fishtail Sword Fern qualifies for 13 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 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 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

Fishtail Sword Fern is also known as Fishtail Sword Fern, Fishtail Fern, and Sickle-leaved Sword Fern.

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