Why are my fern fronds turning brown?

This is usually a sign of low humidity or the soil drying out too much.

How often should I water it?

Keep the soil consistently moist but never waterlogged.

Plant guide

Boston fern.

Nephrolepis exaltata

Pronounced nef-roh-LEP-iss eg-zal-TAY-tuh

Also known as Boston Swordfern, Boston fern, Boston sword fern, Sword Fern, fishbone fern, niʻaniʻau, southern sword fern

The Boston fern is a classic houseplant known for its lush, arching fronds that bring a touch of the tropics indoors. It thrives in humid environments and makes a stunning display in hanging baskets. You will love how its feathery texture softens any room.

At a glance

Care level: Moderate
Plant type: Fern
Light: Filtered light or partial shade
Indoor light: Bright indirect
Water: Every 3 to 7 days
Mature size: 3 feet tall and wide
Growth rate: Medium
Hardiness: USDA 9 to 11

Care

Keep the soil consistently moist but never soggy to prevent root issues. High humidity is key, so misting the fronds or using a pebble tray helps keep it happy. Watch for brown, crispy tips which often signal the air is too dry.

Watering: Water when the top inch of soil feels slightly dry to the touch.
Feeding: Feed with a balanced liquid fertilizer diluted to half strength during the growing season.
Pruning: Trim away any yellow or brown fronds at the base to encourage fresh growth.
Repotting: Move to a slightly larger pot once the roots have filled the current container.
Soil: Peat based potting mix
Soil pH: 6.0 to 7.5
Temperature: 15 to 24°C
Humidity: 50 to 80%
Drought tolerance: Low
Lifespan: Perennial, typically 5 to 10 years with proper care.
Deer and rabbits: Moderate

Signs it needs repotting

Roots growing out of the drainage holes.
Water running straight through the soil without soaking in.
The plant stops growing despite good conditions.

Safety

People: This plant is considered non toxic to humans.
Pets: This plant is non toxic to cats and dogs.
Children: The long, arching fronds can be a tripping hazard or tempting for children to pull on, potentially causing the pot to fall.
Contact allergens: The fronds can be slightly irritating to sensitive skin if brushed against repeatedly.
Airborne allergens: Spore production can occasionally trigger mild respiratory reactions in sensitive individuals.
Edibility: This plant is not intended for consumption.

How to identify it

Arching, feathery green fronds
Small leaflets along the stem
Dense, bushy growth habit
Spreads via underground runners

Height: 0.5 to 1.5m
Spread: 0.5 to 1.5m
Leaves: bright green, evergreen
Flowers: 0cm

Problems to watch for

Scale InsectsCommon
Tip BurnCommon
Fungus GnatsUncommon
Spider MitesUncommon

By symptom

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Growing it

Propagation: division, spores, runners
When to plant: spring, summer
Overwintering: Keep the plant away from cold drafts and heating vents during winter. Maintain consistent moisture, though growth will slow down significantly.
In containers: It grows beautifully in hanging baskets or pots, provided the container has good drainage and is at least 20 cm wide.

Division

1. Carefully remove the plant from its pot.
2. Gently tease the root ball apart into smaller sections.
3. Repot each section into fresh, well draining potting mix.
4. Water thoroughly and keep in a warm, humid spot.

Group ferns together to create a microclimate that helps maintain higher humidity levels.

Grows well with

Peace Lily · They share similar requirements for shade and high humidity.
Pothos · They create a lush, tropical look when grouped together.

Similar species

Bird's Nest Fern · It is another popular, humidity loving indoor fern.

Science

Family: Nephrolepidaceae
Genus: Nephrolepis
Order: Polypodiales
Class: Polypodiopsida
Native range: Tropical regions of the Americas, Africa, and Polynesia.
Conservation: This species is common and not of conservation concern.

It grows as an epiphyte or terrestrial plant in humid, shaded forest floors.

Uses: indoor houseplant, hanging baskets, patio decor

Through the year

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Flowering

Fruiting

Foliage

Ecological indicators

Salinity: 1/9
Soil reaction: 5/9
Light: 3/9
Temperature: 7/9
Moisture: 7/9
Nutrients: 4/9

Taxonomy resolved against GBIF.

Questions people ask

Why are my fern fronds turning brown?: This is usually a sign of low humidity or the soil drying out too much.
How often should I water it?: Keep the soil consistently moist but never waterlogged.

Where the name comes from

The name Nephrolepis comes from the Greek words for kidney and scale, referring to the shape of the spore covers. The specific epithet exaltata means tall or lofty.

Good to know

It is one of the most popular indoor ferns in the world.
The Boston fern is actually a cultivar of the sword fern.
It thrives in the high humidity of a bathroom.

Also in

Plants for shade

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This guide was generated with AI on September 26, 2026 and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.