Rata
Metrosideros bartlettii
A critically threatened Northland rātā bearing distinctive white flowers. It requires warm, frost‑free conditions, free‑draining soils and shelter from salt‑laden winds. Plant only from legally sourced, disease‑free material and support biosecurity and predator control in the wild. Learn more about our threatened species .
Description
Evergreen tree with glossy leaves and remarkable white flowers typical of rātā. Naturally restricted to far‑north sites where climate is mild and moist.
Key Identification
White rātā flowers (unusual within the genus), leathery leaves and a compact crown; requires warm, frost‑free, well‑drained positions in cultivation.
Quick Facts
Content for Metrosideros bartlettii ( Metrosideros bartlettii ).
| Scientific Name | Metrosideros bartlettii |
|---|---|
| Height | 2-8 m (varies with site) |
| Spread | Forms clumps or patches |
| Water Needs | Low to moderate; free-draining soils |
| Light | Sun to light shade |
| Frost Tolerance | High - tolerant of severe freezes |
| Salt Tolerance | Low to moderate |
| Growth Rate | Slow to moderate |
| Lifespan | Long-lived perennial |
Climate Suitability
Content for Metrosideros bartlettii ( Metrosideros bartlettii ).
| City | Climate Suitability |
|---|---|
| Whangārei | Suitable |
| Auckland | Suitable |
| Hamilton | Suitable |
| Tauranga | Suitable |
| Rotorua | Suitable |
| Gisborne | Suitable |
| New Plymouth | Suitable |
| Napier | Suitable |
| Whanganui | Suitable |
| Palmerston North | Suitable |
| Wellington | Suitable |
| Nelson | Suitable |
| Christchurch | Suitable |
| Dunedin | Suitable |
| Invercargill | Suitable |
Habitat
Natural Distribution
Endemic to Te Tai Tokerau/Northland, this species survives as scattered trees in warm, lowland forest remnants of the far north. It favours fertile, free‑draining soils on foothills and sheltered gullies, often on weathered volcanic or sedimentary substrates, with high light at the canopy edge and good airflow. Its natural range is extremely restricted and fragmented, making local microclimate and site protection critical.
Conservation Status
Current Threats and Protection
Listed as Nationally Critical due to tiny population size, recruitment failure and threats including browsing, invasive plants, and myrtle rust risk within the Myrtaceae. Priority actions include protecting mature trees, enhancing seedling recruitment under managed canopies, excluding stock and browsers, and maintaining biosecurity hygiene for myrtle rust. Supplementary plantings should use rigorously disease‑free, legally sourced material.
How to Grow
Cultivation Requirements
Grow in mild, frost‑free districts with long warm seasons. Choose a sunny to lightly dappled site with fertile, free‑draining soil and shelter from harsh coastal winds. Water regularly through the first two summers; mulch to conserve moisture but keep the trunk base clear. Avoid wounds to minimise pathogen entry and adopt myrtle‑hygiene protocols when working nearby.
Planting Guide
Best Planting Practices
Plant in late spring once soils are warm. Amend heavy ground with coarse drainage material and organic matter to improve structure. Set plants at the same depth as the nursery root collar, water to settle, and stake only where exposure demands it. Space away from concrete or compacted areas so roots can explore well‑aerated soil.
Ecological Role
Environmental Benefits
As a canopy tree with profuse white flowers, Bartlett’s rātā provides nectar and pollen for a range of insects and supports forest structure and shading in warm lowland ecosystems. Its rarity elevates the conservation value of sites where it persists.
Uses
Traditional and Modern Applications
Metrosideros bartlettii is a critically valued species for native gardens, particularly in Northland, and is essential for specialized horticultural collections focused on rare New Zealand flora. It plays a crucial role in restoration projects aimed at preserving this unique rata, offering significant ecological and aesthetic value.
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
Metrosideros bartlettii generally requires minimal pruning. Focus on removing any dead, damaged, or diseased growth as needed to maintain plant health and appearance. Light formative pruning can be done to encourage a more compact shape, but avoid heavy cuts, as rātā are sensitive to large pruning wounds, especially in areas with myrtle rust.
How to Grow Rata
From Seed
Propagation of Metrosideros bartlettii from fresh seed is a primary method, though often specialized for conservation purposes. Collect seeds from mature capsules in late summer to autumn. Sow the fine seeds onto a free-draining seed-raising mix, lightly covering them or pressing them onto the surface. Warmth and high light are crucial for germination. Maintain consistent moisture and provide temperatures around 18-25°C (65-77°F). Germination can be erratic and slow, often taking several weeks to months. Due to its critically threatened status, seed propagation is typically undertaken by licensed nurseries or conservation projects, requiring careful handling and myrtle-rust hygiene protocols to prevent pathogen spread.
From Cuttings
Metrosideros bartlettii can also be propagated from semi-hardwood cuttings taken in late spring or summer. Select healthy, non-flowering shoots about 10-15 cm long. Remove the lower leaves and dip the cut end in a rooting hormone to encourage root development. Insert the cuttings into a free-draining rooting medium such as a mix of sand and perlite. Provide high humidity (e.g., under mist or in a propagation chamber) and bottom heat (around 20-25°C or 68-77°F) in a bright, sheltered environment. Rooting typically occurs within 8-16 weeks. Once rooted, gradually acclimatize plants to ambient conditions before potting up. All equipment and handling should follow strict myrtle-rust hygiene protocols.
General Cultivation
Bartlett's Rātā is a critically threatened species that requires warm, frost-free conditions, free-draining soils, and shelter from harsh winds to thrive. It performs best in mild, sheltered sites with long warm seasons. Choose a sunny to lightly dappled site with fertile, free-draining soil. Enrich heavy ground with coarse drainage material and organic matter to improve structure. Water regularly through the first two summers, and mulch to conserve moisture but keep the trunk base clear. Avoid planting where its large leaves could be exposed to strong, salt-laden winds, which can cause damage. Due to the threat of myrtle rust, avoid wounds to minimise pathogen entry and adopt strict myrtle-hygiene protocols when working nearby. Plant only from legally sourced, disease-free material and support biosecurity and predator control in the wild.
Pests and Diseases
Common Problems and Solutions
Myrtle rust is an emerging threat to Myrtaceae-avoid handling in wet weather, disinfect tools and clothing, and report suspect symptoms. Browsing, scale insects and psyllids may occur; good airflow and plant health reduce impacts.
Cultural Significance
Traditional Uses and Values
Rātā and pōhutukawa are iconic to Aotearoa and hold deep cultural significance. Protecting kaumātua trees and restoring their forest context supports whakapapa connections and the resilience of northern ngahere.
Bonus Tip
Expert Growing Advice
Given its "Nationally Critical" status and susceptibility to myrtle rust, growing Metrosideros bartlettii requires strict biosecurity protocols. Always use legally sourced, disease-free material, and minimize handling, especially in wet weather, to prevent pathogen spread. Focus on excellent air circulation and well-drained soil.
