Boston fern (sword fern)
Nephrolepis exaltata
Evergreen tropical fern with arching, feathery fronds; popular as a houseplant and landscape fern. Prefers bright indirect light, high humidity and consistently moist, well-draining soil.
Pet-Friendly Plant
Toxicity: non toxic
Boston fern is considered non-toxic to cats and dogs; ingestion may cause minor digestive upset but is not poisonous.
🌱Care Requirements
Light
Place the Boston (sword) fern in bright, indirect light — near an east or north-facing window or 1–2 m back from a bright south/west window. Avoid direct midday sun which scorches fronds; filtered light through a sheer curtain is ideal.
Water
Keep soil evenly moist but not waterlogged. Water thoroughly until water drains, then allow the top 1–2 cm (0.5–1 in) to dry before watering again. Reduce frequency in cooler months but never let the root ball dry out completely.
Humidity
Requires consistently high humidity (50–80%). Use pebble trays, frequent misting, grouping with other plants, or a humidifier. Bathrooms and kitchens often provide good ambient humidity if light is adequate.
Temperature
Prefers 15–27°C (60–80°F). Avoid cold drafts below 13–15°C (55–60°F) and sudden temperature swings which cause frond browning or drop.
🔧Common Problems & Solutions
Brown, crispy frond tips or edges
Cause: Low humidity, underwatering, or salt buildup from tap water
Solution: Increase humidity with misting or humidifier, water evenly, flush soil occasionally to remove salts and trim damaged tips.
Yellowing lower fronds
Cause: Natural aging, overwatering, or poor drainage causing root stress
Solution: Remove old fronds, check drainage and potting mix, reduce watering frequency and repot if roots are rotting.
Fronds wilting or collapsing
Cause: Underwatering, root-bound plant, or root rot from prolonged saturation
Solution: Inspect roots; water thoroughly if dry, repot into fresh mix if root-bound, and cut away rotten roots before replanting.
Small webbing, speckled fronds or sticky residue
Cause: Spider mites, scale or mealybugs in dry conditions
Solution: Increase humidity, wipe fronds with soapy water, use insecticidal soap or neem oil, and isolate affected plants.
✂️How to Propagate Boston fern (sword fern)
Best propagated by division in spring. Remove plant from pot and gently tease or cut the root ball into sections with several healthy fronds and roots each. Trim any damaged roots. Repot divisions into fresh, well-draining, peat-rich potting mix, water to settle soil, and keep in bright indirect light with high humidity until established.
🌍Origin & Background
Family: Nephrolepidaceae
Native to: Tropical and subtropical Americas, Caribbean and western Africa regions.
Natural Habitat: Grows in humid, shaded understories of tropical forests, along stream banks and slopes, often in humus-rich soils or as epiphytic clumps on tree trunks with constant moisture and dappled light.
🗓Seasonal Care Guide
Winter
Reduce watering frequency but keep soil slightly moist; maintain humidity and keep plant away from cold drafts and heating vents. Lower light may require moving closer to a bright window.
Spring
Increase watering and resume light fertilizing with a balanced, diluted fertilizer. Divide and repot if rootbound; refresh top layer of potting mix and boost humidity.
Summer
Keep in bright, indirect light with consistent moisture and high humidity. Protect from hot direct sun and ensure good air circulation to prevent pests.
Fall
Gradually reduce fertilizing and slightly lower watering as growth slows. Keep humidity up and inspect for pests before bringing plants indoors for colder climates.
❓Frequently Asked Questions
How often should I water a Boston fern?
Water when the top 1–2 cm is slightly dry, typically every 3–7 days indoors; adjust for temperature and pot size.
Why are my Boston fern fronds turning brown?
Usually low humidity, underwatering, or direct sun. Increase humidity, trim brown tips, and check watering routine.
Can I keep a Boston fern in low light?
It tolerates low light but grows best in bright, indirect light; too little light causes sparse, leggy fronds.
Is Boston fern safe for pets?
Yes, Nephrolepis exaltata is considered non-toxic to cats and dogs, though eating plant material may upset stomachs.
When is best time to repot or divide a Boston fern?
Spring is ideal—repot or divide when new active growth begins and soil warms for quick recovery.
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Last updated: 11/7/2025