How to grow fishbone fern
Overview
Fishbone fern (Nephrolepis cordifolia) is a clumping, evergreen fern grown for its arching, finely divided fronds. It is valued as a filler in shaded garden beds and containers, providing year-round texture. This fern spreads by underground runners and can naturalise in moist, sheltered spots.
Varieties
- Nephrolepis cordifolia 'Duffii' — A compact, bushy form with shorter fronds, ideal for small pots and terrariums.
- Nephrolepis cordifolia 'Kimberly Queen' — Upright, narrow fronds that hold their shape well; popular for indoor and outdoor use.
Soil Preparation
Fishbone fern prefers slightly acidic to neutral soil (pH 5.5–7.0) rich in organic matter. Amend heavy clay with compost and coarse sand to improve drainage. A loamy, well-aerated mix with added leaf mould or peat moss suits it best.
Growing Guide
Plant fishbone fern in well-draining, humus-rich soil in a part-shade to full-shade position, avoiding harsh afternoon sun. Space divisions 30–40 cm apart for a groundcover effect. Keep the soil consistently moist but not waterlogged; water deeply once or twice a week in dry weather. Mulch around the base to retain moisture and suppress weeds. It establishes quickly in warm, humid conditions and benefits from regular misting in dry spells.
Care
Feed with a balanced liquid fertiliser (e.g., seaweed or fish emulsion) every 4–6 weeks during spring and summer. Prune yellowing or dead fronds at the base to keep the plant tidy and encourage new growth. Divide overcrowded clumps in early spring every 2–3 years to maintain vigour and prevent centre die-off.
Companion Planting
Fishbone fern pairs well with other shade lovers such as bromeliads, clivia, and cordyline. Underplant with mondo grass or native violets for a lush, layered look. Avoid planting near aggressive spreaders like bamboo or running grasses that may compete for root space.
Common Pests & Risks
Scale insects and mealybugs can infest the fronds, especially in humid conditions. Treat with horticultural oil or soap spray, targeting the undersides of leaves. Check for fern mites (tiny, pale pests) that cause stippling; use a miticide if needed. Keep plants well-spaced to improve air circulation and reduce pest pressure.
Troubleshooting
Yellowing fronds: usually overwatering or poor drainage; let soil dry slightly between waterings. Brown frond tips: low humidity or dry air; mist regularly or move to a more sheltered spot. Stunted growth: lack of nutrients; apply a balanced liquid fertiliser. Spreading too fast: trim back runners or grow in a container to contain roots.