Maidenhair Fern
Adiantum cunninghamii
The Cunningham's Maidenhair Fern (scientific name: Adiantum cunninghamii ) is a graceful and widely distributed terrestrial fern endemic to New Zealand . A prominent member of the Pteridaceae family, it is easily identified by its delicate, fan-shaped leaflets and smooth, wiry stems. Found from the Kermadec Islands to the Southern Alps, it is a characteristic component of coastal and lowland forest understories. One of its most striking features is the contrast between its dark green upper leaf surfaces and the pale, glaucous blue-green of the undersides. Understanding this fern contributes to the appreciation of our rich botanical heritage and supports conservation efforts for all native species.
Plant Description
Identification and Physical Characteristics
Adiantum cunninghamii typically grows in tufted clumps, reaching heights between 15 and 35 cm. It possesses short- to long-creeping rhizomes that allow it to form extensive, spreading colonies over time. The fronds are ovate to elliptic in shape and are typically 2-3-pinnate at the base. The leaflets are oblong and often curve gently upward at the tips, featuring irregularly toothed outer margins. The stems, or stipes, are remarkably thin, hairless, and have a polished dark appearance. Sori are protected by distinctive kidney-shaped indusia located along the recurved margins of the leaflets. Its name, derived from the Greek word for 'not moistened,' refers to the characteristic ability of the foliage to shed water.
Quick Facts
| Scientific Name | Adiantum cunninghamii |
|---|---|
| Height | 150-350mm tall |
| Spread | Creeping widely via rhizomes |
| Water Needs | High - consistent moisture required |
| Light | Deep to partial shade - no direct sun |
| Frost Tolerance | Moderate - protect from heavy frosts |
| Salt Tolerance | Low - inland forest species |
| Growth Rate | Slow initially, vigorous once established |
| Lifespan | Long-lived perennial with proper care |
Climate Best Suited to
Adiantum cunninghamii is well adapted to various New Zealand regions.
Regional Suitability
| City | Climate Suitability |
|---|---|
| Auckland | High |
| Wellington | High |
| Christchurch | Medium |
Plant Habitat
Natural Occurrence and Ecology
Cunningham's Maidenhair Fern is common throughout New Zealand's coastal and lowland forests, occasionally extending into montane regions up to 1100 meters. It thrives in a variety of shaded and moist environments, including shaded banks, boulder fields, and damp forest margins. It is particularly associated with limestone outcrops and other mineral-rich substrates like greywacke, sandstone, and scoria. This adaptable fern can also be found on wet rock faces near waterfalls, in small caves, and along the banks of permanent rivers and gullies. It prefers bright but humid shade where it is protected from direct sunlight and strong, drying winds.
Growing Requirements
Soil Requirements
Prefers well-draining soil rich in organic matter.
- Well-drained
- Loamy
Light Requirements
Grows best in partial to full sun.
- Full Sun
- Partial Shade
Water Requirements
Requires regular watering during dry periods.
- Regular
- Drought tolerant once established
Planting and Establishing
Establishment Guidance
Establishing Cunningham's Maidenhair Fern in a garden requires creating an environment that mimics its cool, humid forest home. It must be planted in a position with bright, indirect light and consistently moist, free-draining soil rich in humus or organic matter. Choose a sheltered spot that is protected from sudden temperature shifts and direct afternoon sun. Dig a hole slightly larger than the root ball and plant at the same depth as it was in its container. Regular watering is essential during its first few seasons to help establish its creeping rhizome system, after which it can become a durable and long-lived ground cover in a shaded native garden.
Ecological Role
Biodiversity and Ecosystem Impact
In its native ecosystems, Adiantum cunninghamii plays a significant role as a structural component of the forest floor and bank communities. Its dense, spreading growth helps to stabilize steep slopes and riparian margins, preventing soil erosion. The multi-layered canopy of fronds creates stable micro-habitats with high humidity, supporting specialized native invertebrates and providing a sheltered environment for the regeneration of other forest plants. The minute spores are wind-dispersed, allowing the fern to efficiently colonize new areas of suitable habitat. Its presence is often an indicator of a healthy, intact forest understory with stable moisture and light levels.
Uses & Significance
Garden Uses
Cunningham's Maidenhair Fern is a highly prized choice for native ferneries, shaded rockeries, and limestone-themed gardens. Its exquisite foliage and unique blue-green undersides provide a beautiful visual interest that works well in close-up viewing areas. Because it spreads via rhizomes, it is an excellent native ground cover for filling gaps under larger shrubs or along shaded pathways. It is also an elegant option for indoor plant collections, thriving in terrariums or hanging baskets where its graceful, layered habit can be showcased to its full potential.
- Shaded ground cover
- Rock garden detail
Ecological Value
Ecologically, it is a valuable species for restoration projects in lowland and coastal forests. It supports local biodiversity by providing habitat for ground-dwelling invertebrates and contributes to the overall aesthetic and biological richness of New Zealand's native forest remnants.
- Invertebrate habitat
- Soil stabilization
Landscaping Uses
In professional landscape design, Cunningham's Maidenhair Fern is used to add a sense of refined elegance and textural depth to shaded spaces. Its dark stems and contrasting green foliage provide a sophisticated palette that works well in contemporary native garden themes. It is ideal for mass planting along shaded banks or used as a soft filler between architectural stone features and limestone boulders. The way its fronds catch the light and movement in the breeze adds a dynamic, horizontal element to the garden design. Its resilience and ability to form persistent colonies make it a reliable and low-maintenance choice for high-quality native landscaping.
Seasonal Care Calendar
Spring
The start of the active growth surge. Remove any spent or damaged fronds from the previous year to make room for fresh new growth from the creeping rhizomes. This is an ideal time to apply a very light organic native fertilizer.
- Fertilize
- Mulch
Summer
Ensure the soil remains consistently moist during the heat of summer. Misting the fronds during early morning or evening can help maintain the high humidity this fern requires to prevent the delicate leaflets from scorching.
- Water
- Check for pests
Autumn
Growth begins to slow as the weather cools. Tidy the area around the base of the fern and ensure no heavy fallen leaves from larger shrubs are smothering the delicate fronds, which can encourage fungal issues in the damp autumn air.
- Prune lightly
- Plant new specimens
Winter
Naturally very hardy but benefits from a sheltered position during severe freezes. Requires minimal care during the dormant months; simply avoid any heavy foot traffic or disturbance to the root zone while the ground is frozen.
- Frost protection
When to Prune and How Much
Cunningham's Maidenhair Fern requires almost no conventional pruning to stay healthy. Maintenance is generally limited to the occasional removal of old, brown, or crossing fronds to maintain a fresh and tidy appearance. This should be done using sharp, sterilized scissors to cut the thin, wiry stems as close to the base as possible. Avoid pulling the fronds off by hand, as this can damage the delicate creeping rhizomes. Always use clean tools to prevent the introduction of pathogens to the plant and to ensure quick recovery.
- Remove dead branches
Always use clean, sharp tools.
How to Grow Cunningham's Maidenhair Fern
Cultivating Cunningham's Maidenhair Fern ( Adiantum cunninghamii ) is a rewarding pursuit for the patient native gardener. This graceful species can be propagated through several effective methods, allowing you to easily increase your stock of this iconic plant. Success depends on providing the humid, well-drained, and shaded conditions it thrives in throughout its native New Zealand forest home.
From Seed
Propagation from spores is possible but requires specific techniques and a sterile environment. Spores should be collected from the ripe, dark sori along the leaf margins. Sow them onto the surface of a sterilized, moist peat-based mix and keep in a warm, brightly lit spot under a clear cover to maintain high humidity. Germination can be slow and sporadic, but it is an excellent way to produce a large number of healthy new ferns.
Sow fresh seeds in a seed-raising mix.
- Collect seeds
- Sow in trays
Keep moist until germination.
From Cuttings
The most reliable and fastest method for home gardeners is the division of established clumps. In early spring, carefully lift a section of the rhizomatous root system, ensuring each division has several healthy fronds and a portion of the creeping rhizome. Replant these immediately into a rich, moist potting mix and keep in a sheltered, humid position until new growth is evident and the root system has established.
Take semi-hardwood cuttings in late summer.
- Take cuttings
- Use rooting hormone
Additional Methods
Depending on the growth habit of Adiantum cunninghamii , other methods such as division or layering might also be viable options. Division is particularly suitable for plants that form dense clumps or have spreading root systems, while layering can be used for species with trailing or flexible stems.
Young ferns are sensitive to drying out and must be kept in a consistently moist environment during their first few seasons. They are best established in a site free from aggressive competition from larger weeds. A top-dressing of fine organic mulch or leaf mould around the base will help regulate soil moisture and provide the humid conditions the delicate fronds require to thrive and spread naturally.
- Divide clumps
- Replant immediately
Pests & Diseases
Cunningham's Maidenhair Fern is generally resistant to most major garden pests. Occasionally, scale insects or mealybugs may target the wiry stems in stagnant conditions. The primary health risk is root rot, which can occur if the fern is grown in heavy, waterlogged soils with poor air circulation. Choosing a well-ventilated, shaded position with perfect drainage is the best way to ensure the long-term health of your fern and to prevent any physiological issues.
Cultural Significance
Named after the 19th-century botanist Allan Cunningham, this fern is a significant part of New Zealand's botanical heritage. Its graceful form and unique water-shedding properties have long been appreciated by both Māori and early European settlers. While not as extensively used as larger tree ferns, it remains an iconic symbol of the delicate beauty of the New Zealand forest floor. Today, it is valued by conservationists and native plant enthusiasts alike for its resilience and the exquisite detail it brings to our native landscapes.
- Traditional medicine
- Crafts
Bonus Tip
To truly highlight the unique blue-green undersides of the leaflets, plant Cunningham's Maidenhair Fern on a raised bank or in a hanging basket. This allows you to view the fronds from below, where the beautiful colour contrast is most visible and effective.
Related Plants
Explore other native plants that share similar characteristics or habitats with Adiantum Cunninghamii ( Adiantum cunninghamii ), offering further insights into New Zealand's diverse flora. These related species provide context and opportunities for complementary planting in your garden.
Plant Conservation
Conservation Status
Currently classified as 'Not Threatened' nationally, Cunningham's Maidenhair Fern remains a stable and significant component of New Zealand's native flora. Its wide distribution across various islands and habitats ensures its continued success. However, its long-term survival is linked to the preservation of native forest understories and coastal environments from development and the spread of invasive weeds. Protecting these habitats and ensuring the health of the entire forest ecosystem are key strategies for maintaining the status of this iconic endemic fern.