Rasp Fern
Doodia australis
Doodia australis, also known as Rasp Fern or by its Māori name Pukupuku, is a hardy New Zealand native fern renowned for its distinctive textured fronds and vibrant pink-red new growth. This compact terrestrial fern forms spreading clumps up to 30-45cm high and 50cm wide, making it an excellent choice for shaded gardens and rockeries. The species is recognized by its rough, raspy-textured mature fronds that feel somewhat like a raspberry to the touch, hence its common name. Young emerging fronds display attractive pink to red coloration due to protective flavonoids before gradually maturing to lush green, creating a beautiful contrast of colors within a single colony.
Plant Description
Doodia australis (rasp fern) forms neat rosettes of narrow pinnae on upright fronds; new growth often flushed pink to bronze, maturing green. Compact and well-behaved for small shade gardens.
Quick Facts
| Scientific Name | Doodia australis (syn. Blechnum parrisiae) |
|---|---|
| Common Name | Rasp Fern, Pukupuku, Fragrant Fern |
| Plant Type | Hardy terrestrial fern |
| Height | 30-45cm |
| Spread | 30-50cm spreading clumps |
| Fronds | Textured, raspy to touch; pink-red when young, maturing to green |
| Growth Habit | Clumping, creeping outwards to form colonies |
| Distribution | North Island (Te Paki to Wellington), South Island (Marlborough, Nelson, Banks Peninsula), Three Kings, Kermadec Islands |
| Habitat | Coastal to lowland forest, river margins, alluvial forest, damp fertile soils |
| Conservation Status | Not Threatened |
| Water Needs | Moderate - prefers evenly moist, well-drained soil |
| Light | Light shade to dappled light, can tolerate some sun |
| Frost Tolerance | Hardy, suitable for temperate climates |
| Salt Tolerance | Good - suitable for coastal conditions |
| Growth Rate | Moderate, spreads readily |
| Lifespan | Perennial, long-lived |
| Propagation | Very easy from fresh spores, self-sows readily |
| Distinctive Features | Textured fronds, pink new growth, spreading habit |
Climate Best Suited to
Mild, humid shade; tolerates light frost with protection and dislikes hot, dry wind.
Regional Suitability
| City | Climate Suitability |
|---|---|
| Whangārei | Ideal |
| Auckland | Ideal |
| Hamilton | Ideal |
| Tauranga | Ideal |
| Rotorua | Ideal |
| Gisborne | Ideal |
| New Plymouth | Ideal |
| Napier | Ideal |
| Whanganui | Ideal |
| Palmerston North | Ideal |
| Wellington | Ideal |
| Nelson | Ideal |
| Christchurch | Ideal |
| Dunedin | Ideal |
| Invercargill | Ideal |
Natural Habitat
Rasp Fern occupies damp, well‑drained soils on shaded forest margins, stream banks and alluvial terraces from coastal to lowland sites. It favours humus‑rich leaf litter and filtered light, often forming small colonies where spores find bare, moist ground to germinate. In warmer regions it also persists on sheltered rock faces and among boulders where seepage maintains even moisture.
The species is tolerant of wind and occasional dry spells once established, provided its roots can access cool, organic‑rich substrate. In mixed fern understories it weaves between larger crowns, adding fine texture and seasonal colour from pink new fronds.
Plant Conservation
Doodia australis has a conservation status of "Not Threatened" according to the New Zealand Threat Classification System. This classification reflects the species' stable populations and wide distribution across suitable habitats in New Zealand.
The species demonstrates remarkable resilience and adaptability, readily establishing from wind-dispersed spores and often self-seeding in suitable garden conditions. This natural propagation ability, combined with its hardy nature and broad habitat tolerance, contributes to its secure conservation status. The fern's ability to colonize disturbed sites and form spreading colonies also aids in its conservation, as it can quickly reestablish in suitable areas.
How to Grow
Provide bright shade, steady moisture and humus‑rich, free‑draining soil. Shelter from hot, drying winds helps keep fronds pristine; avoid waterlogging the crown, especially in winter. Mulch with leaf litter to mimic forest conditions and conserve moisture.
Planting Guide
Plant in spring into loose, humus‑rich soil with the crown at or slightly above the final surface. Water to settle, then mulch with leaf litter or fine bark, keeping mulch off the crown. Space 30-45 cm apart for a continuous, low fern carpet.
Ecology
Acts as a small‑scale ground binder on shady banks, trapping leaf litter and creating cool, moist micro‑habitats for invertebrates. As colonies expand from spore, they help knit soil on slopes and under light canopy where periodic disturbance occurs.
Uses
Excellent for edging shaded paths, tucking between boulders, softening the base of larger tree ferns and filling pockets in shaded rock gardens. Compact habit suits containers and courtyard ferneries where red new growth provides seasonal contrast.
Landscaping Ideas
Layer with Asplenium bulbiferum, Blechnum novae-zelandiae juveniles and shade‑tolerant Astelia cultivars for contrasting textures. Use repeating clumps along a shaded path to create rhythm and highlight fresh, coloured fronds in spring.
Seasonal Care
Summer
Maintain even moisture and humidity through dry spells; avoid harsh afternoon sun and hot winds to prevent crisping. Rinse foliage during dusty periods to keep fronds clean.
Pruning
In late winter, remove tatty or spent fronds cleanly at the base. Avoid cutting into the crown. Groom lightly through the season to showcase new red growth, taking care not to damage emerging croziers.
How to Grow Rasp Fern
Rasp Fern grows best when you match its natural habitat: prepare well-drained soil, get the light right, water steadily, and protect from extremes during establishment. Dig wide planting holes, set the crown at original depth, water to settle, and mulch with coarse organic matter to conserve moisture while keeping the stem base dry. Feed lightly in spring; heavy nitrogen is unnecessary and can weaken growth.
Seed
Sow fresh, viable seed on a free-draining mix, cover lightly with fine grit, and keep evenly moist in bright light out of harsh sun. Germination timing varies; prick out once roots hold the media and harden off gradually.
Division
Where the species permits, divide robust clumps in early spring as new growth begins. Replant divisions with several shoots into fresh mix, water thoroughly, and maintain steady moisture until re"established.
Cuttings
For shrubs and many perennials, strike semi-hardwood cuttings in late spring to summer in a coarse, free-draining propagation mix under gentle bottom heat and high humidity. Reduce leaf area, ventilate progressively as roots develop, and pot on before planting out.
Aftercare
Maintain an open mulch, irrigate during drought in the first season, and prune or tidy according to the species to build a resilient framework. Adjust shade, wind exposure and watering to prevent stress, and refresh mulch annually for long-term performance.
Pests and Diseases
Generally trouble‑free. In dry indoor or enclosed sites, scale and mealybug can settle on older stipes-wash with a mild soap spray and improve airflow. Slugs and snails chew tender croziers; use traps and hand‑picking. Crown rot occurs if soil remains saturated.
Cultural Significance
The Rasp Fern holds cultural significance for Māori, who know it by the traditional name Pukupuku. This name reflects the plant's importance in traditional ecological knowledge and its recognition as a distinctive member of New Zealand's indigenous flora. The fern's hardy nature and attractive appearance have made it valued both traditionally and in contemporary New Zealand gardens.
In traditional Māori culture, native ferns like Doodia australis were recognized for their ecological roles and often used as indicators of soil fertility and environmental conditions. The species' preference for fertile, well-drained soils made it a useful indicator plant for areas suitable for cultivation or settlement.
Modern conservation efforts recognize the importance of native species like the Rasp Fern in maintaining New Zealand's unique botanical heritage. The plant's ease of cultivation and attractive appearance have made it popular in native plant restoration projects and indigenous garden designs, helping to connect contemporary New Zealanders with their natural heritage.
Bonus Tip
Use collected rainwater and a thin leaf‑litter mulch to mimic forest duff; both reduce spotting on delicate fronds and keep the crown evenly moist without smothering it.
Related Plants
Discover other native New Zealand plants that share similar growing conditions and complement the natural beauty of Doodia australis in your garden design.
