Narrow swordfern
Nephrolepis cordifolia · Nephrolepidaceae
📷 Forest & Kim Starr · CC BY 3.0
The gardener's calendar
Ideal time to plant narrow swordfern: set it out when the soil is neither frozen nor waterlogged, and water generously as it establishes.
ID card
- Foliage
- Evergreen, bright green
- Growth
- Fast to moderate
- Adult height
- 30 to 50 cm
- Ideal exposure
- Indirect light, partial shade
- Water requirement
- Moderate, moist soil but not waterlogged
- Hardiness
- Cold sensitive, 10 °C minimum
- Origin
- Tropical and subtropical regions
- Soil type
- Light potting mix, well-draining, rich in organic matter
✓ Taxonomy verifiedSource: AI estimate · hardiness: reliability medium.
Expert tips
The key tip
Nephrolepis cordifolia loves humid air, but not waterlogged soil. Place the pot on damp pebbles without submerging the roots.
The common mistake
Keeping it outdoors outside tropical climates: with zero frost hardiness, it deteriorates at the first frosts or prolonged cold without heating.
The pro's trick
In a Mediterranean climate, grow it under a cold frame or unheated conservatory in winter, in the shade outside in summer: it thrives this way for 30 years in a pot with minimal maintenance.
Care
Watering
Keep the substrate moist but never waterlogged: water as soon as the top 2 centimetres dry out slightly. Ideally, use non-calcareous or rainwater. In winter, space out watering according to temperature and ambient light. Ferns appreciate a humid atmosphere: mist the foliage regularly or place the pot on a humidified tray.
Light exposure
The tuberous sword fern thrives in indirect light, away from a south-facing window or behind a sheer curtain. Avoid direct sun rays which scorch the foliage. Conversely, insufficient light slows growth and weakens the plant. A location near a north or north-east facing window is optimal.
Soil and substrate
Use a light mix made up of universal potting soil, peat or coco fibre and perlite to ensure good aeration and efficient drainage. Ferns hate compact soil and root asphyxiation. Repotting every 2 to 3 years in spring allows you to refresh the substrate and prevent nutrient depletion.
Fertilizer
Apply a balanced fertilizer, diluted to half-strength, every 3 to 4 weeks during the growing season (April to September). Reduce applications in autumn and suspend them in winter. Ferns are sensitive to overdoses: under-feeding is less damaging than excess nutrients which burn the roots.
Pruning and maintenance
Regularly remove yellow, dried or damaged fronds at the base to promote a attractive shape. Gentle cleaning of the foliage with a damp cloth removes dust and improves photosynthesis. Avoid harsh products: plain water is quite sufficient.
Pests and diseases
Watch for spider mites and mealybugs, favoured by dry air. Increase ambient humidity through regular misting to prevent these pests. Root rot can occur if water is persistently excessive: immediately reduce watering and improve pot drainage.
Did you know?
Nephrolepis cordifolia has been cultivated since the 19th century in Victorian Europe, where it embodied the bourgeois prestige of exotic plants. Its nickname 'sword fern' comes from the slender and slightly undulating shape of its fronds. Unlike many ferns, it produces small underground tubers that allow it to survive drier periods, a rare asset in the Nephrolepidaceae family.
Where to buy it
Plant in spring or early autumn, avoiding spells of intense heat. Pick a plant with healthy foliage and roots that are not exposed. Best time: March, April, May, September.
Add this plant to my garden →Plants from the same family
- Boston swordfernNephrolepis exaltata
- Giant swordfernNephrolepis biserrata
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- CamelliaCamellia japonica
- Pedunculate oakQuercus robur
- SageSalvia officinalis
Tips generated and checked by Viridia — adapt them to your local climate.