Forest Cabbage Tree (Cordyline banksii) hero image

Forest Cabbage Tree

Cordyline banksii

Not Threatened

This native plant, known as Forest Cabbage Tree (scientific name: Cordyline banksii), is a remarkable 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 Palms.

Forest Cabbage Tree (Cordyline banksii) showing its elegant drooping foliage
Image credit: Forest Cabbage Tree (Cordyline banksii) - photo by Wikipedia contributors, via Wikipedia

Plant Description

Cordyline banksii, known as the Forest Cabbage Tree or Tī Ngahere, is a distinctive and elegant member of the Asparagaceae family. Unlike the more common Cordyline australis, this species often grows as a shrub or small tree with multiple stems arising from the base, reaching heights of up to 4 metres. Its most striking feature is its foliage; the leaves are exceptionally long, often between 1 and 2 metres, and quite narrow at 4 to 8 centimetres wide. These leaves have a prominent midrib and a glossy green surface, gracefully arching and drooping towards the ground, giving the plant a soft, fountain-like appearance. In late spring and summer, it produces large, open panicles of small, creamy white flowers that emit a sweet, heavy fragrance, followed by small, bluish-white berries that are a favourite for native birds.

Quick Facts

Cordyline banksii quick facts
Scientific Name Cordyline banksii
Height Up to 4 metres
Spread 2-3 metres
Water Needs Moderate
Light Full sun to partial shade
Frost Tolerance Hardy to -4°C
Salt Tolerance High
Growth Rate Moderate
Lifespan 50-100 years

Climate Best Suited to

Forest Cabbage Tree thrives in a range of New Zealand climates but is most at home in the North Island and the northern South Island. It prefers temperate conditions with reliable rainfall and can tolerate coastal winds and salt spray.

Regional Suitability

City suitability for Forest Cabbage Tree
City Climate Suitability
Auckland Excellent
Wellington Very Good
Christchurch Good (in sheltered spots)
Nelson Excellent
Hamilton Very Good

Plant Habitat

Tī Ngahere is found throughout the North Island and the northern half of the South Island, extending as far south as Westland. It is a versatile plant that naturally inhabits a range of environments, from coastal cliffs and lowland forests to montane shrublands. It is particularly fond of forest margins, stream banks, and steep, rocky slopes where it can find sufficient light and drainage. While it thrives in the dappled light of the forest understory, it is also frequently seen in more open coastal scrub, where it demonstrates its resilience to wind and salt spray.

Growing Requirements

Soil Requirements

Prefers moist, well-draining soils with plenty of organic matter.

  • Well-drained loam
  • Moist forest soils
  • Rocky or sloping ground

Light Requirements

Adaptable to various light levels but performs best in bright, indirect light.

  • Partial shade (ideal)
  • Dappled sunlight
  • Full sun (if soil remains moist)

Water Requirements

Requires regular moisture during establishment and dry spells.

  • Consistent summer watering
  • Drought tolerant once mature
  • Avoid waterlogged conditions

Planting and Establishing

When planting Cordyline banksii, choose a position that allows for its arching leaves to spread without obstruction. Dig a hole twice the width of the root ball and enrich the soil with compost. Ensure the plant is set at the same depth as it was in the container. Firm the soil around the base and water deeply. Applying a layer of mulch will help retain moisture and keep the roots cool, which is beneficial for this forest-dwelling species.

Ecological Role

Forest Cabbage Tree plays a vital role in New Zealand ecosystems by providing food and habitat for native wildlife. Its sweetly scented flowers attract a wide variety of pollinators, including native bees, butterflies, and nectar-feeding birds like tūī and bellbirds. The subsequent berries are a significant food source for kererū and other forest birds, which in turn help disperse the seeds throughout the forest.

Uses & Significance

Garden Uses

With its architectural form and lush foliage, Tī Ngahere is a popular choice for New Zealand gardens.

  • Feature plant in tropical-style gardens
  • Underplanting for larger native trees
  • Coastal landscaping
  • Slope and bank stabilization

Ecological Value

Provides essential resources for native biodiversity in both forest and garden settings.

  • Pollinator attraction with fragrant blooms
  • Bird food from prolific berries
  • Habitat for native insects

Landscaping Uses

In landscaping, Cordyline banksii is often used to create a layered effect. Its mid-sized height makes it a perfect bridge between ground covers and taller canopy trees. The drooping leaves provide a soft texture that contrasts well with the more rigid forms of other native plants like Phormium or Pseudopanax. It is particularly effective when planted in groups to create a lush, forest-floor aesthetic.

Seasonal Care Calendar

Spring

Apply a slow-release fertilizer and refresh mulch layers to prepare for new growth.

  • Fertilize before new shoots appear
  • Monitor for pests
  • Plant new specimens

Summer

Ensure the plant remains hydrated during dry periods to prevent leaf scorch.

  • Regular deep watering
  • Monitor fragrance and bird activity
  • Remove any dead lower leaves

Autumn

Collect mature seeds for propagation and prepare the plant for the cooler months.

  • Seed collection
  • Check for adequate drainage
  • Reduce watering frequency

Winter

The plant is relatively dormant; avoid heavy pruning or disturbance during this time.

  • Protect young plants from heavy frost
  • Minimal maintenance required

When to Prune and How Much

Forest Cabbage Tree requires minimal pruning. Its growth habit is naturally tidy and attractive.

  • Remove dead or damaged leaves at the base
  • Prune spent flower panicles if desired for a cleaner look
  • Remove any crossing or rubbing stems in multi-stemmed specimens

Always use clean, sharp tools to avoid introducing disease. If the plant becomes too tall or leggy, it can be "topped" to encourage branching, although this will temporarily alter its natural fountain-like form.

How to Grow Forest Cabbage Tree

Cultivating Forest Cabbage Tree (Cordyline banksii) is a rewarding endeavour for any gardener interested in New Zealand's unique flora. This species can be propagated through several methods, each requiring specific conditions to ensure healthy growth and establishment. Successful propagation depends on mimicking the plant's natural environment and providing consistent care during the early stages of development. It is much more tolerant of shade than the common cabbage tree, making it ideal for planting under the canopy of larger trees or in south-facing gardens.

From Seed

Propagation from seed is often the most effective way to produce a large number of Forest Cabbage Tree plants. Seeds should be collected when they are fully mature, typically in late autumn when the berries have turned a bluish-white. Freshly collected seeds generally have higher germination rates than those that have been stored for long periods.

To sow from seed, follow these steps to ensure the best possible success rate for your new plants:

  1. Remove the fleshy pulp from the seeds by soaking them in water for 24 hours.
  2. Sow the clean seeds into a tray filled with a high-quality seed-starting mix.
  3. Cover lightly with soil and keep the mix consistently moist but not waterlogged.
  4. Place the tray in a warm, sheltered spot out of direct sunlight.
  5. Germination typically occurs within 4 to 8 weeks.

Once the seedlings have produced two or three true leaves, they can be carefully transplanted into individual pots. Grow them on in a sheltered area for at least a year before planting them out into their permanent positions in the garden.

From Cuttings

For those wishing to replicate specific characteristics of a parent plant, vegetative propagation via cuttings is the preferred method. This technique ensures that the new plants are genetically identical to the source. Semi-hardwood cuttings taken during the appropriate season usually yield the best results for this species.

Stem cuttings can be taken from the main trunk or from side shoots. Simply cut a section of stem approximately 10-15 centimetres long, remove the lower leaves, and dip the base in rooting hormone. Place the cutting in a free-draining potting mix and keep it in a humid, warm environment until roots begin to form.

  1. Take 10-15cm cuttings from healthy, non-flowering stems.
  2. Remove lower leaves to expose nodes.
  3. Dip in rooting hormone if desired.
  4. Insert into a mix of peat and perlite or sand.
  5. Keep moist and in a warm, shaded location.

Additional Methods

Depending on the growth habit of Forest Cabbage Tree, 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.

Multi-stemmed specimens can occasionally be divided at the root level during the dormant winter period. Ensure each division has a healthy portion of roots and several stems. Replant immediately and water thoroughly to help the new plants establish without undue stress.

  1. Carefully excavate around the base of a multi-stemmed plant.
  2. Identify a section with its own root system.
  3. Use a sharp spade to separate the division from the parent.
  4. Replant in a suitable location with improved soil.

Pests & Diseases

Cordyline banksii is generally robust but can be affected by the Cabbage Tree Moth (Epiphryne verriculata), whose caterpillars feed on the leaves, creating characteristic notched edges. Scale insects and mealybugs may also occasionally appear. "Cabbage Tree Decline," caused by the phytoplasma Candidatus Phytoplasma australiense, is a more serious issue affecting Cordyline species, although C. banksii often shows more resilience than C. australis.

Cultural Significance

Tī Ngahere holds significant cultural value for Māori. Like other Cordyline species, it was used for a variety of purposes. The young inner leaves and the tender growing tip (koata) were eaten as a vegetable. The fibrous leaves were processed to make durable ropes, fishing lines, and textiles.

  • Traditional food source (kauru)
  • Fiber for weaving and cordage
  • Medicinal uses for leaf extracts

Bonus Tip

If you want to attract more tūī to your garden, plant several Forest Cabbage Trees together. Their heavy summer fragrance and abundant nectar are irresistible to native birds, creating a lively and vocal environment during the flowering season.

Plant Conservation

While Cordyline banksii is currently classified as "Not Threatened," it still faces pressure from habitat loss and browsing by introduced pests such as possums and rats. Promoting its use in urban gardens and restoration projects helps ensure its long-term survival and provides essential links in the ecological corridors that support our native birds.