Lemon button fern (Nephrolepis cordifolia 'Duffii') care

Ferns · straightforward to keep

Last updated 26 October 2026

Lemon button fern (Nephrolepis cordifolia 'Duffii') wants medium indirect light. Water it every 4 days. Keep the compost damp at all times — this is the one plant on this list where 'let it dry out' is wrong. Standing the pot in a shallow tray of water for an hour once a week suits it. Pot it in moisture-retentive peat-free compost with perlite. A weak balanced feed monthly in spring and summer, and repot once a year. Humidity: above 60%. A fern in dry air is a fern on its way out. Not on the ASPCA's list itself, only its relatives, so we don't call it pet-safe.

Lemon button fern: a compact sword fern with tiny round leaflets on short fronds. Small and neat enough for a shelf or a terrarium, and as thirsty as any fern.

Quick facts

Water: Water every 4 days. Keep the compost damp at all times — this is the one plant on this list where 'let it dry out' is wrong. Standing the pot in a shallow tray of water for an hour once a week suits it.
Light: Medium indirect light.
Humidity: Above 60%. A fern in dry air is a fern on its way out.
Soil: Moisture-retentive peat-free compost with perlite.
Feeding: A weak balanced feed monthly in spring and summer.
Repotting: Repot once a year.
Toxic to pets: Not on the ASPCA's list itself, only its relatives, so we don't call it pet-safe. Keep it out of reach of a pet that chews. The ASPCA does not list Nephrolepis cordifolia 'Duffii' itself, but lists a relative, Bold Sword Fern (Nephrolepis biserrata), as non-toxic to cats and dogs (checked 26 October 2026).
Difficulty: Straightforward.
Mature size: 20–30 cm tall.
Native to: A cultivated form; the species grows across the tropics.

Watering a Lemon button fern

Water every 4 days. Keep the compost damp at all times — this is the one plant on this list where 'let it dry out' is wrong. Standing the pot in a shallow tray of water for an hour once a week suits it.

That cadence is the one PlantParlour sets for this species when you name it, and it is deliberately on the cautious side — a plant that asks a day early is safer than one that asks a day late. Log each watering and the reminder moves with the plant rather than with the calendar.

Light

Medium indirect light, and never direct sun. A bright north window or a well-lit bathroom is close to ideal.

Humidity and temperature

Above 60%. A fern in dry air is a fern on its way out. Central heating in winter is what turns a comfortable room into a dry one, and it is the usual reason an established plant suddenly browns at the edges or picks up spider mites.

Soil and potting

A mix that holds water without turning to mud: compost with perlite and a little bark. Ferns have fine roots that must never dry out completely.

Feeding

A weak balanced feed monthly in spring and summer. Stop feeding in autumn and start again when you see new growth in spring — feeding a plant that isn't growing just builds up salts in the pot.

Repotting

Repot once a year. Every spring. Divide the clump at the same time if it has filled the pot.

Common problems

Fronds going brown and crisp from the tips
Dry air, or the compost dried out.

Fix: Raise the humidity and never let the pot go fully dry. A bathroom is the easy answer.

Brown tips and edges: how to read it on any plant
Leaflets dropping all over the floor
Dry heat, usually from a radiator.

Fix: Move it away from the heat source and raise the humidity.

Leaves falling off: how to read it on any plant
Yellowing fronds in a wet pot
It is sitting in water rather than damp compost.

Fix: Damp, not waterlogged — make sure the pot drains and the saucer empties.

Yellow leaves: how to read it on any plant
Brown dots in rows under the fronds
Spores. Completely normal.

Fix: Nothing to do; it means the fern is mature and happy.

Propagation

Divide the clump in spring. Spores work but take the better part of a year.

A cutting taken in PlantParlour keeps its link to the plant it came from, so a propagation years later still traces back to the mother plant — which is the point if you ever sell or trade it.

Toxicity and safety

Not on the ASPCA's list itself, only its relatives, so we don't call it pet-safe. Keep it out of reach of a pet that chews.

The ASPCA does not list Nephrolepis cordifolia 'Duffii' itself, but lists a relative, Bold Sword Fern (Nephrolepis biserrata), as non-toxic to cats and dogs (checked 26 October 2026).

If your pet has eaten a plant, call your vet, the ASPCA Animal Poison Control Center on (888) 426-4435, or the Pet Poison Helpline on (855) 764-7661. Both are open around the clock and may charge a consultation fee. Take the plant or its label with you.

This is general information, not veterinary advice. We don't test plants: what we say about toxicity follows the ASPCA's published plant list as it stood on 26 October 2026, and that list can change. "Non-toxic" means not poisonous — a pet that eats enough of any plant can still vomit, and fertiliser, pesticide or leaf shine on a plant can harm it. It also only helps if the plant is what you think it is. It covers cats and dogs only; ask your vet about rabbits, birds, reptiles or anything else, and a doctor about children. Read our terms.

Every houseplant in the library the ASPCA lists as non-toxic to cats and dogs

Questions people ask

How often should you water a Lemon button fern?

Water every 4 days as a starting point — that is the cadence PlantParlour sets for Nephrolepis cordifolia 'Duffii'. Keep the compost damp at all times — this is the one plant on this list where 'let it dry out' is wrong. Standing the pot in a shallow tray of water for an hour once a week suits it. Light, pot size and the time of year all move that number, so treat it as a reminder to go and check rather than a rule.

How much light does a Lemon button fern need?

Medium indirect light, and never direct sun. A bright north window or a well-lit bathroom is close to ideal.

Is Lemon button fern toxic to cats and dogs?

Not on the ASPCA's list itself, only its relatives, so we don't call it pet-safe. Keep it out of reach of a pet that chews. The ASPCA does not list Nephrolepis cordifolia 'Duffii' itself, but lists a relative, Bold Sword Fern (Nephrolepis biserrata), as non-toxic to cats and dogs (checked 26 October 2026). If a pet has eaten part of a plant, call your vet or the ASPCA Animal Poison Control Center on (888) 426-4435 straight away.

How do you propagate a Lemon button fern?