Boston fern (Nephrolepis exaltata) care

Ferns · needs attention to keep

Boston fern (Nephrolepis exaltata) 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. Non-toxic to cats and dogs.

The Boston fern: arching fronds of fine leaflets, the Victorian parlour plant that never went away. It wants what no centrally-heated room offers — constant damp and humid air — which is why it is best kept in a bathroom, and why it sheds leaflets over the carpet everywhere else.

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: Non-toxic to cats and dogs.
Difficulty: Needs attention.
Mature size: 50–90 cm tall and wide.
Native to: Tropical America; the cultivar arose in Boston in 1894.

Watering a Boston 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.
Leaflets dropping all over the floor
Dry heat, usually from a radiator.

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

Non-toxic to cats and dogs.

Questions people ask

How often should you water a Boston fern?

Water every 4 days as a starting point — that is the cadence PlantParlour sets for Nephrolepis exaltata. 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 Boston fern need?