Kōwhai
Sophora longicarinata
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Sophora longicarinata (long-keel kōwhai) bears clusters of yellow pea-flowers with a pronounced keel. It favours limestone and fertile alluvial soils in sunny, well-drained locations.
Identification
Sophora longicarinata is characterized by its pinnate leaves with numerous small leaflets, and vibrant yellow pea-flowers featuring a distinctively long keel. These flowers develop into pods containing hard, toxic seeds. It can be distinguished from other kōwhai species by the specific length of its keel and the size and arrangement of its leaflets.
Quick Facts
| Scientific Name | Sophora longicarinata |
|---|---|
| Common Name | Long-keel kōwhai |
| Family | Fabaceae |
| Height | 2-8 m (varies with site) |
| Spread | Forms clumps or patches |
| Water Needs | Moderate; avoid waterlogging |
| Light | Full sun |
| Frost Tolerance | Moderate |
| Salt Tolerance | Low to moderate |
| Growth Rate | Slow to moderate |
| Lifespan | Long-lived perennial |
Climate Best Suited to
Sophora longicarinata, the long-keel kōwhai, thrives in mild to cool temperate climates with good rainfall and well-drained soils. It is well-suited to regions that experience moderate frosts and benefits from ample sunlight. Its adaptability allows it to perform well across various parts of the country, particularly on limestone and fertile alluvial soils.
| 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
occurs in natural habitats characteristic of Aotearoa, forming part of distinctive plant communities where site stress and local disturbance shape vegetation patterns. 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. These preferences explain its patchy distribution and sensitivity to changes in hydrology, competition and disturbance regimes. Sophora longicarinata
Conservation Status
Current Threats and Protection
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. Sophora longicarinata Populations of
How to Grow
Cultivation Requirements
Provide free‑draining soils and high light appropriate to the species’ natural range. Choose warm, sunny sites with shelter from the fiercest onshore winds; avoid heavy, waterlogged soils. Maintain steady moisture without stagnation by planting on gentle berms or well‑structured loams.
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.
Ecology
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. Sophora longicarinata
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.
Landscaping Ideas
Combine with compatible natives to echo its natural associates, and use stony or leaf‑litter mulches to reinforce the intended microclimate. Avoid cramped beds; allow room for the plant’s mature form to read as a clear structural element.
Seasonal Care
Year-Round Maintenance
Spring: check ties and remove winter damage. Summer: water deeply but infrequently to promote deep roots. Autumn: refresh mulches and reduce irrigation as growth slows. Winter: ensure drainage and exposure are maintained, especially on heavy soils.
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 Kōwhai
From Seed
Propagation of Sophora longicarinata from seed is a common method, but requires pre-treatment due to the hard seed coat and dormancy. Collect mature pods when they are dry and yellow-brown. Extract the hard, smooth, yellow-brown seeds (note: seeds are toxic if ingested). Seeds require scarification (nicking the seed coat with a file or sandpaper) or hot-water treatment (pour boiling water over seeds, let soak overnight, then sow) to allow water uptake and germination. Sow treated seeds in spring onto a well-drained seed-raising mix, lightly covering them. Maintain consistent moisture and warmth (around 18-24°C or 65-75°F). Germination typically occurs within a few weeks after treatment. Once seedlings are robust enough to handle, prick them out into individual pots and grow them on in a sheltered, bright location until strong enough for planting out.
From Cuttings
Sophora longicarinata can be propagated from semi-hardwood cuttings taken in late summer to early autumn. Select healthy, firm stem segments, about 10-15 cm long, from the current season's growth. Remove the lower leaves and dip the cut end in a rooting hormone to encourage root development. Insert the cuttings into a gritty, sterile, free-draining rooting medium such as a mix of sand and perlite. Provide gentle bottom heat (around 18-24°C or 65-75°F) and high humidity around the cuttings, either by placing them in a propagation chamber or covering them with a plastic bag. Keep in a warm, bright location out of direct sunlight. Rooting typically occurs reliably within 8-16 weeks. Grafting is also possible for selected forms or to ensure genetic purity.
General Cultivation
Long-keeled Kōwhai (Sophora longicarinata) is a handsome small tree suitable for gardens and restoration plantings, known for its clusters of yellow pea-flowers with a pronounced keel. It prefers warm, sunny sites with free-draining soils and high light. It favours limestone and fertile alluvial soils. Avoid heavy, waterlogged soils. While moderately frost-tolerant, it benefits from shelter from the fiercest onshore winds, particularly when young. Maintain steady moisture without stagnation by planting on gentle berms or well-structured loams. Mulch to conserve moisture and suppress weeds during establishment. Minimal pruning is required; remove dead or crossing material after flowering and avoid hard renovation cuts. Protect young plants from browsing where deer, goats or rabbits are present.
Pests and Diseases
Common Problems and Solutions
Good siting prevents most problems-sharp drainage and appropriate exposure are key. Protect young plants from browsing where deer, goats or rabbits are present.
Cultural Significance
Traditional Uses and Values
Sophora longicarinata, like other kōwhai species, holds cultural importance for Māori, symbolizing new life and growth. Its vibrant yellow flowers attract native birds such as tūī, enhancing biodiversity and contributing to the ecological health of its habitat. Cultivating this species supports conservation efforts and connects to indigenous heritage.
Bonus Tip
Expert Growing Advice
To maximize flowering and attract native birds like tūī, plant Sophora longicarinata in a sunny, sheltered position with free-draining soil, particularly on limestone or fertile alluvial sites. Its distinctive long-keeled yellow pea-flowers provide vital nectar resources. Minimal pruning helps maintain its natural form.
