Chatham Island Kakaha
Astelia chathamica
A bold, clump-forming Astelia native to the Chatham Islands, prized for its broad, silver-green leaves that arch from a central crown. It thrives in cool, moist but free-draining soils with shelter from the harshest winds, making it ideal for coastal and woodland gardens. coastal .
Plant Description
Evergreen, clump-forming monocot with bold, strap-shaped leaves arising from a central crown. Leaf undersides may be paler or silvery. Panicles of small flowers are followed by fleshy fruits on female plants. Architectural foliage provides year-round structure.
Quick Facts
| Scientific Name | Astelia chathamica |
|---|---|
| Family | Asteliaceae |
| Form | Bold, clump-forming evergreen with strappy leaves |
| Light | Bright shade to part sun; shelter from scorching winds |
| Soil | Moist, free-draining, humus-rich; avoid waterlogging |
| Water | Moderate; regular moisture, especially in summer |
| Height | 2-8 m (varies with site) |
| Spread | 40-120 cm across |
| Water Needs | High - consistent moisture |
| Frost Tolerance | High - tolerant of severe freezes |
| Salt Tolerance | Moderate to high (coastal species) |
| Growth Rate | Slow to moderate |
| Lifespan | Long-lived perennial |
Climate Best Suited to
Mild coastal to temperate climates; protect from hard frost and drying winds.
Regional Suitability
| City | Climate Suitability |
|---|---|
| Auckland | Ideal |
| Wellington | Ideal |
| Nelson | Ideal |
| Christchurch | Moderate |
| Whangārei | Suitable |
| Hamilton | Suitable |
| Tauranga | Suitable |
| Rotorua | Suitable |
| Gisborne | Suitable |
| New Plymouth | Suitable |
| Napier | Suitable |
| Whanganui | Suitable |
| Palmerston North | Suitable |
| Dunedin | Suitable |
| Invercargill | Suitable |
Plant Habitat
occurs in natural habitats characteristic of Aotearoa, forming part of distinctive plant communities where site stress and local disturbance shape vegetation patterns. It favours exposed slopes, screes or fellfields with thin, rapidly drained mineral soils, enduring intense radiation, wind and freeze-thaw cycles. On the coast it occupies sunny, wind‑prone sites with sandy or rocky substrates, where salt‑laden air and periodic drought limit competition. Along waterways and wetlands it persists on better‑drained margins, terraces and riparian fringes where periodic flooding and fresh silt create establishment niches. In forest it typically grows in bright shade at edges and canopy gaps, on fertile but free‑draining soils protected from extreme heat and desiccation. These preferences explain its patchy distribution and sensitivity to changes in hydrology, competition and disturbance regimes. Astelia chathamica
Plant Conservation
are influenced by land use, browsing and weeds. Protecting intact habitat mosaics, reducing browser pressure, and managing invasive plants sustain recruitment. Where local stands are small or isolated, eco‑sourced augmentation and careful site stewardship help secure long‑term viability. Astelia chathamica Populations of
Growing Requirements
Soil
Humus-rich, free-draining; add composted leaf mould and fine bark; avoid boggy sites.
Light
Bright shade to part sun; protect from harsh afternoon sun in hot districts.
Water
Regular moisture; mulch to conserve water and keep roots cool.
Planting Guide
Best Planting Practices
Plant in the cool, moist months into weed‑free ground. Set plants slightly proud of the surrounding soil, water to settle, and mulch with coarse gravel or woodchips while keeping the stem base clear. Grouping two to three plants replicates natural patterns and improves establishment under local conditions.
Ecological Role
Environmental Benefits
contributes structure and seasonal resources where it grows, providing cover and habitat for invertebrates and, when flowering or fruiting, nectar, pollen or seed for fauna. By tolerating the stresses of its environment, it helps stabilise sites and enrich small‑scale habitat diversity. Astelia chathamica
Uses
Traditional and Modern Applications
Ideal for rock and gravel gardens that emulate alpine processes, or for specialised collections. Suited to sunny, maritime gardens with sandy or rocky soils where wind and salt are considerations. Fits woodland and understory schemes beneath open canopies, especially in restoration plantings.
Landscaping Uses
Garden Design Applications
Excellent for rock gardens, alpine collections, and naturalistic plantings. Best used in open, well-drained positions where its distinctive form can be appreciated. Combines well with other native alpine plants and provides year-round structure. Consider placement carefully due to sharp foliage - avoid high-traffic areas. Creates dramatic focal points in contemporary and native-themed garden designs.
Seasonal Care
Year-Round Maintenance
Spring management focuses on removing winter-damaged foliage and assessing drainage. Summer care emphasizes maintaining adequate moisture without waterlogging. Autumn preparation includes reducing irrigation and ensuring good air circulation. Winter protection may require covering in areas subject to excessive moisture. Year-round monitoring ensures early detection of problems and maintenance of optimal growing conditions.
Pruning
Pruning Techniques
Little pruning is required; remove dead or crossing material after flowering and avoid hard renovation cuts. Light tip‑pruning maintains compact form without compromising the plant’s natural character.
How to Grow Chatham Island Kakaha
From Seed
Propagation from seed is possible but requires patience. Collect the fleshy berries when they turn bright orange in late summer or autumn. Remove the pulp to clean the seeds, as the fruit flesh can inhibit germination. Sow the cleaned fresh seed onto a moist, well-drained seed-raising mix. Cover lightly with grit or vermiculite. Maintain a warm temperature and consistent humidity. Germination can be slow and erratic, sometimes taking several months. Once seedlings are large enough to handle, prick them out into individual pots. Note that plants grown from seed will be variable and may take several years to reach a garden-worthy size.
From Division
Division is the most common and effective method for propagating Astelia chathamica, ensuring you get a plant identical to the parent. The best time to divide established clumps is in spring or early autumn. Carefully lift the entire plant or use a sharp spade to slice off healthy side shoots (offsets) from the outer edge of the clump. Ensure each division has a good portion of roots and a fan of leaves. Trim the foliage back by about a third to reduce water loss while the new roots establish. Replant the divisions immediately into prepared soil or containers and water well.
General Cultivation
Astelia chathamica is a stunning architectural plant that thrives in cool, moist, and well-drained conditions. It prefers a position with partial shade or dappled light, although it can tolerate full sun in cooler coastal areas if the soil remains moist. Protection from strong, drying winds is essential to prevent the beautiful silver foliage from becoming wind-burned or shredded. The soil should be rich in humus and free-draining; heavy, waterlogged soils can lead to crown rot, particularly in winter. Mulching with organic matter helps keep the root run cool and moist, mimicking its natural forest floor habitat. Once established, it is reasonably drought-tolerant but looks best with regular watering during dry spells.
Pests & Diseases
Good siting prevents most problems-sharp drainage and appropriate exposure are key. Crown and root rots arise if winter wet persists; keep crowns elevated and water moving. In still, shaded corners, sap‑suckers and sooty mould may appear; improve airflow and wash foliage if needed. Protect young plants from browsing where deer, goats or rabbits are present.
Cultural Significance
Chatham Icon
known as 'Kakaha' or 'Moriori Flax', this plant is culturally significant to the Chatham Islands. Its striking silver foliage makes it a standout feature of the island's unique flora.
Bonus Tip
The Best Silver
Astelia chathamica 'Silver Spear' is widely considered the best silver-foliaged structural plant for New Zealand gardens. It keeps its metallic sheen year-round and is far more robust than many other silver plants.
