Crimson Rata
Metrosideros carminea
This native plant, known as Crimson Rata (scientific name: Metrosideros carminea), is a spectacular species endemic to New Zealand. It is characterized by its unique features, ecological role, and cultural significance. This comprehensive guide provides detailed information on its care, propagation, and importance within the New Zealand ecosystem. Understanding this plant contributes to the appreciation of our rich biodiversity and heritage, and supports conservation efforts for Native Climbers.
Plant Description
Metrosideros carminea, commonly known as Crimson Rata or Akakura, is a woody climbing liane that can scale heights of up to 15 metres or more. It is celebrated for its stunning profusion of carmine-red flowers which appear in dense, fluffy clusters during the spring months. The plant displays distinct juvenile and adult forms. Juvenile growth is often flat and hairy, clinging tightly to host trees or rock faces using small aerial roots. Adult leaves are small, glossy, leathery, and dark green, providing a beautiful backdrop for the vibrant floral display. When grown from cuttings taken from adult wood, the plant often maintains a compact, shrubby habit rather than a climbing one.
Quick Facts
| Scientific Name | Metrosideros carminea |
|---|---|
| Height | Up to 15 metres (Climbing) |
| Spread | Variable |
| Water Needs | Moderate to High |
| Light | Full sun to partial shade |
| Frost Tolerance | Sensitive to heavy frost (especially young) |
| Salt Tolerance | Moderate |
| Growth Rate | Moderate |
| Lifespan | Long-lived perennial |
Climate Best Suited to
Crimson Rata is native to the North Island of New Zealand, traditionally found from the far north down to Taranaki and the Mahia Peninsula. It prefers warm, temperate climates with consistent moisture. While it enjoys a sheltered position, it needs plenty of light to flower well. Mature plants are reasonably hardy to light frosts, but young specimens are vulnerable and should be protected during their first few winters.
Regional Suitability
| City | Climate Suitability |
|---|---|
| Auckland | Excellent |
| Wellington | Very Good |
| Christchurch | Good (Shelter Required) |
| Dunedin | Marginal |
| Hamilton | Good |
| Tauranga | Excellent |
Plant Habitat
In the wild, Crimson Rata inhabits coastal to lowland forests and forest margins. It is particularly adept at colonizing rock outcrops and cliff faces, where it can be seen trailing beautifully. It is also a common climber on large forest trees, using their structures to reach the light of the upper canopy. It thrives in well-drained, humus-enriched soils and is often found near waterways where humidity is higher.
Plant Conservation
Recently classified as 'Threatened - Nationally Vulnerable', Metrosideros carminea faces a significant threat from Myrtle Rust (Austropuccinia psidii). This fungal disease affects many species in the Myrtaceae family, including Rata and Pohutukawa. Conservation efforts focus on monitoring wild populations and securing genetic material in nurseries to ensure the long-term survival of the species against this biological threat.
Growing Requirements
Soil Requirements
Humus-rich and Well-drained
- Prefers soil with high organic matter content.
- Must be free-draining to avoid root issues.
- Tolerates a range of soil types if moisture is consistent.
Light Requirements
Full Sun to Part Shade
- Needs plenty of sun to produce the best floral displays.
- Enjoys partial shade for its roots and lower stems.
- Ideal for growing against north or west-facing walls.
Water Requirements
Consistent Moisture
- Requires regular watering, especially during dry summer periods.
- Does not tolerate prolonged drought well.
- Annual mulching helps retain essential root moisture.
Planting Guide
Choose a planting site that provides a cool, moist root run and a sunny area for the upper parts of the plant to grow. For climbers, plant near a wall, rock face, or established tree. If you have a shrubby form (grown from adult wood), it can be planted as a specimen in a garden border. Autumn and spring are the best planting seasons. Prepare the soil by digging in plenty of compost. Ensure the plant is not buried deeper than it was in its pot. After planting, water thoroughly and apply a generous layer of bark or leaf mulch around the base, keeping it away from the main stems to prevent rot.
Ecological Role
Crimson Rata is a vital source of spring nectar for native birds, including Tūī, Bellbirds, and Stitchbirds. Its flowers also attract a variety of native insects and bees. By scaling forest giants, it adds complexity to the forest structure, providing niches for smaller epiphytes and insects within its tangled climbing stems. It is a key component of a healthy, diverse North Island forest ecosystem.
Uses & Significance
Garden Uses
Vertical Colour
- Spectacular climber for covering walls and rock features.
- The shrubby form makes an excellent low-growing specimen.
- Brings vibrant spring colour and attracts native wildlife.
Ecological Value
Bird Support
- Important early spring nectar source for native birds.
- Contributes to forest biodiversity and structure.
- Supports conservation efforts for Threatened Myrtaceae.
Cultural Significance
Known as Akakura to Māori, the Crimson Rata is recognized for its beauty and the nectar it provides. The vibrant red of its flowers is often associated with the forest's life force. Like other Rata species, it is part of the traditional botanical knowledge of Aotearoa, prized for the way it brightens the forest margins in spring. It remains a symbol of the unique and colourful biodiversity of the North Island's temperate forests.
- Traditional name is Akakura.
- Celebrated for its vibrant carmine-red spring floral display.
- Symbol of the North Island's forest life force.
Landscaping Uses
In landscaping, Crimson Rata is a top choice for adding vertical interest and intense seasonal colour. It is particularly effective when trained against stone or brick walls where its aerial roots can gain purchase. The shrubby cultivars, which stay low and spreading, are excellent for garden borders or as groundcovers on banks. Due to its coastal tolerance, it is also a good option for sheltered coastal gardens. Its ability to attract native birds makes it a favorite for gardeners looking to create a bird-friendly environment.
Seasonal Care Calendar
Spring
Flowering and Feeding
- Enjoy the peak carmine floral display.
- Apply a slow-release fertiliser for new growth.
- Ensure roots are well-watered as growth flushes occur.
Summer
Moisture and Maintenance
- Water regularly during dry summer spells.
- Maintain a thick mulch layer to keep roots cool.
- Lightly prune after flowering to maintain shape.
Autumn
Planting and Preparation
- Excellent time for new plantings in warmer regions.
- Replenish mulch for the coming year.
- Monitor for any signs of Myrtle Rust.
Winter
Protection and Rest
- Protect young or sensitive plants from heavy frost.
- Minimal watering required during dormancy.
- Check ties and supports on climbing vines.
When to Prune and How Much
Crimson Rata responds well to light pruning, which helps maintain a tidy habit and encourages fresh flowering wood.
- Best pruned immediately after flowering has finished in late spring.
- Remove any dead or diseased stems back to healthy wood.
- Lightly trim new growth to maintain a compact form if growing as a shrub.
- Avoid heavy pruning into old, leafless wood as it may be slow to recover.
Always use sharp, sterilized tools to make clean cuts, which helps prevent the spread of diseases like Myrtle Rust.
How to Grow Crimson Rata (Metrosideros carminea)
From Seed
Growing Crimson Rata (Metrosideros carminea) from seed is the only way to ensure the plant maintains its natural climbing habit. The seeds are produced in small woody capsules that ripen several months after flowering. When the capsules begin to turn brown and open, collect them and place them in a paper bag in a warm spot. As they dry, the tiny, needle-like seeds will be released. These seeds are very fine and have a limited shelf life, so they should be sown as soon as possible after collection.
Prepare a seed tray with a fine, sterile seed-raising mix. A blend of peat and fine perlite works well. Surface-sow the seeds, as they require light to germinate. Do not cover them with soil; instead, gently press them into the surface of the mix. Water using a fine mist to avoid washing the seeds away. Place the tray in a warm, bright location (18-22°C) with high humidity. A propagator lid or clear plastic cover is highly beneficial for maintaining moisture.
Germination is typically quick, often occurring within two to three weeks. Once the seedlings are large enough to handle, carefully prick them out and transplant them into individual pots using a high-quality native potting mix. Seed-grown plants initially grow slowly and require consistent moisture and protection from extreme temperatures. They will naturally exhibit their juvenile climbing habit, scaling nearby structures with aerial roots as they mature.
From Cuttings
Cuttings are a popular way to propagate Crimson Rata, especially if you want to create the shrubby form of the plant. Cuttings taken from adult, flowering wood will almost always produce a plant that maintains its adult characteristics and remains as a shrub.
- Take semi-hardwood cuttings in late summer or autumn.
- Select healthy tips approximately 10 cm long.
- Remove the lower leaves and dip the base into a rooting hormone.
- Insert the cuttings into a well-draining propagation mix of peat and sand.
- Provide high humidity and bright, indirect light. Rooting takes several months. Once rooted, pot up and grow on in a sheltered nursery area before planting.
Additional Methods
Layering and Rooted Pieces
- Because the juvenile stems often produce roots as they trail along the ground, you can sometimes find naturally layered pieces. These can be carefully detached and potted up. Ground layering can also be deliberately induced by pinning a juvenile stem to the soil.
Pests & Diseases
The most critical threat is Myrtle Rust, which appears as bright yellow powdery spots on new growth. If you suspect your plant has Myrtle Rust, do not touch it or move it; contact the local biosecurity authorities. Crimson Rata can also be affected by scale insects or leaf-tier caterpillars, which can be controlled with organic sprays. Protection from possums is essential, as they are fond of the foliage.
Bonus Tip
To get the most intense flowering from your Crimson Rata, ensure it is planted in a spot that receives maximum sun, especially during the winter and early spring. The warmth of the sun on the adult foliage is the key trigger for the spectacular carmine-red floral explosion that makes this plant a standout in any garden.
Related Plants
Explore other native plants that share similar characteristics or habitats with Crimson Rata (Metrosideros carminea), offering further insights into New Zealand's diverse flora. These related species provide context and opportunities for complementary planting in your garden.
