Crown Fern
Blechnum discolor
Crown Fern (Blechnum discolor) is a common and attractive ground fern in New Zealand forests, forming dense colonies with its arching fronds. It is valued for its role in forest ecology and as a garden plant. Learn more about New Zealand ferns
Image credit: Crown Fern (Blechnum discolor). Wikipedia
Quick Facts
| Scientific Name | Blechnum discolor |
|---|---|
| Height | 0.5–1.5 m (fronds) |
| Spread | Forms dense colonies, up to several meters across |
| Water Needs | High; prefers consistently moist soil |
| Light | Deep to dappled shade (tolerates some morning sun) |
| Frost Tolerance | Moderate (tolerates light frost, protect from severe frost) |
| Salt Tolerance | Low (not tolerant of coastal salt) |
| Growth Rate | Moderate |
| Lifespan | Perennial (long-lived, colonies can persist for decades) |
Crown Fern is native to the forests of New Zealand, where it thrives in cool, moist, shaded environments. It is found throughout the country in suitable habitats, particularly in damp gullies and forest understories. It prefers areas with consistent moisture and protection from direct sunlight and drying winds.
Regional Suitability
| City | Climate Suitability |
|---|---|
| Whangārei | Moderate |
| Auckland | Moderate |
| Hamilton | Ideal |
| Tauranga | Moderate |
| Rotorua | Ideal |
| Gisborne | Moderate |
| New Plymouth | Ideal |
| Napier | Challenging |
| Whanganui | Moderate |
| Palmerston North | Ideal |
| Wellington | Ideal |
| Nelson | Ideal |
| Christchurch | Moderate |
| Dunedin | Ideal |
| Invercargill | Ideal |
Soil Requirements
Crown Fern performs best in the following soil conditions:
- Rich, humus-filled soil
- Good moisture retention
- Well-draining but consistently damp
- Slightly acidic to neutral pH (5.5-7.0)
- Benefits from added leaf mold or composted pine needles
- Tolerates poor soils if moisture is adequate
Light Requirements
This fern prefers shaded conditions:
- Deep to dappled shade
- Protection from direct sunlight, especially midday sun
- Morning sun tolerated in cooler regions
- Ideal under canopy of trees or larger shrubs
- Can tolerate more light if soil remains consistently moist
- Avoid hot, exposed sites
Water Requirements
Consistent moisture is key for Crown Fern:
- Regular watering to maintain even soil moisture
- Never allow soil to dry out completely
- Reduce frequency in winter but don't let soil dry out
- Benefits from misting in dry conditions
- Mulch to help retain soil moisture
- Good drainage to prevent waterlogging
Temperature Tolerance
Crown Fern has the following temperature preferences:
- Prefers cool to moderate temperatures
- Ideal growing range: 10-24°C (50-75°F)
- Can tolerate light frosts once established
- Protect from severe frost in colder regions
- Dislikes hot, dry conditions
- Provide extra humidity during hot periods
Crown Fern's ecological significance is evident in its role as a key understory species. Its presence indicates a healthy forest ecosystem, and its growth requirements reflect its ecological significance in maintaining forest moisture levels and providing habitat for small forest creatures.
Garden Uses
- Ground cover for shaded gardens and forest plantings
- Used in traditional Māori medicine and for weaving
- Provides habitat for insects and helps retain forest moisture
Spring
Divide clumps and refresh mulch.
Summer
Water during dry spells; provide shade if needed.
Autumn
Remove old fronds and tidy up plants.
Winter
Minimal care needed; protect from severe frost.
Pruning & Maintenance
Crown Fern (Blechnum discolor) requires minimal pruning. Remove dead or damaged fronds at the base to maintain a tidy appearance and encourage healthy new growth. Pruning is best done in late winter or early spring before new fronds emerge. Avoid cutting into the crown of the plant.
Planting Guide
Crown Fern (Blechnum discolor) thrives in shaded, moist environments with well-draining, humus-rich soil. Plant with the crown just above soil level and water regularly, especially during dry spells. Mulch to retain moisture and suppress weeds. Avoid direct sunlight, which can scorch the fronds. Ideal for underplanting in native gardens and forest settings.
Division
The most reliable method for home gardeners:
- Divide established plants in early spring or autumn
- Carefully dig up the entire plant
- Use a sharp knife or spade to separate the crown into sections
- Ensure each division has both roots and fronds
- Replant divisions immediately at the same depth as before
- Water thoroughly and keep consistently moist until established
- Protect new divisions from direct sun and wind
Spores
For those wanting a challenge:
- Collect fertile fronds when spore cases turn brown (usually late summer)
- Place fronds on clean paper in a warm, dry place for 1-2 days
- Collect the fine, dust-like spores that fall onto the paper
- Prepare a sterile growing medium of peat and perlite
- Sprinkle spores thinly over the surface
- Cover with glass or plastic to maintain humidity
- Keep at 18-21°C (65-70°F) in indirect light
- Mist with distilled water to maintain moisture
- Prothalli will form in 1-3 months
- Young ferns will develop in 6-12 months
- Transplant when several fronds have formed
Cultural History
Crown Fern (Blechnum discolor) was used by Māori as a ground cover in traditional gardens and for its fibrous roots, which were sometimes used as a food source in times of scarcity. The plant is valued for its role in native forest ecosystems, providing habitat and soil stability.
Pests & Diseases
Crown Fern (Blechnum discolor) is generally pest-free but can occasionally be affected by slugs and snails, which feed on young fronds. Fungal diseases are rare but may occur in overly wet conditions. Remove affected fronds and improve air circulation if needed.
Create a stunning visual effect by planting Crown Fern in a circular pattern around the base of a native tree or large shrub. The radiating crowns of the ferns echo the circular pattern, creating a natural mandala effect when viewed from above. This arrangement not only looks beautiful but also mimics the way these ferns naturally grow in forest settings. For added interest, intersperse with native ground covers like Pratia angulata (Panakenake) with its tiny white flowers.
