Gardner's Tree Daisy
Olearia gardneri
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Olearia gardneri is a rare New Zealand tree daisy of serious conservation concern in parts of its range. A small tree with narrow leaves and daisy-like heads, it occupies open woodland and shrubland sites and benefits from weed and browsing control.
Identification
Narrow, simple leaves on a small tree or tall shrub. Capitula with white ray florets and yellowish disc florets typical of Asteraceae. Differentiate from other narrow-leaved Olearia by leaf size, venation, and capitulum arrangement.
Quick Facts
| Scientific Name | Olearia gardneri |
|---|---|
| Family | Asteraceae |
| Threat Status | Threatened in parts of range; protect sites |
| Height | 2-8 m (varies with site) |
| Spread | 40-120 cm across |
| 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
Mild to cool temperate sites with sun and free-draining soils.
Regional Suitability
| City | Suitability |
|---|---|
| Wellington | Ideal |
| Nelson | Ideal |
| Christchurch | Ideal |
| Dunedin | Moderate |
| Whangārei | Suitable |
| Auckland | Suitable |
| Hamilton | Suitable |
| Tauranga | Suitable |
| Rotorua | Suitable |
| Gisborne | Suitable |
| New Plymouth | Suitable |
| Napier | Suitable |
| Whanganui | Suitable |
| Palmerston North | Suitable |
| Invercargill | Suitable |
Habitat and 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. 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. Olearia gardneri
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. Olearia gardneri Populations of
How to Grow
Cultivation Requirements
Full sun to light shade; shelter while young. Keep soils free- draining. Prune lightly after flowering. In restoration, control weeds and browsing pressure; use eco-sourced plants where possible.
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. Olearia gardneri
Uses
Traditional and Modern Applications
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 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 Gardner's Tree Daisy
From Seed
Propagation of Olearia gardneri from fresh seed is a viable method, and crucial for conservation efforts. Collect seeds (achenes) from the dried flower heads once they are mature, typically in late summer to autumn. Sow the seeds onto a well-aerated, free-draining seed-raising mix in spring, covering lightly. Asteraceae seeds often benefit from light for germination, so maintain good light exposure. Keep the substrate evenly moist but not saturated, ensuring good air circulation to prevent damping-off. Bottom heat (around 18-24°C or 65-75°F) can aid germination. Germination can be erratic and slow, often taking several weeks to months. Once seedlings are robust enough to handle, prick them out into individual pots and grow them on in a cool, bright, and well-ventilated location until strong enough for planting out.
From Cuttings
Olearia gardneri can be successfully 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 free-draining rooting medium such as a mix of sand and perlite. Provide 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. Once rooted, gradually acclimatize plants to ambient conditions before potting up.
General Cultivation
Gardner's Tree Daisy is a threatened species requiring specific cultivation for conservation and restoration. It thrives in mild to cool temperate sites with full sun and free-draining soils. Plant in well-drained soil; avoid prolonged waterlogging. In its natural habitat, it often grows in bright shade at forest edges and canopy gaps on fertile but free-draining soils. Shelter young plants from harsh winds and intense direct sunlight until well established. Water during establishment; thereafter, only during extended drought. Prune lightly after flowering to maintain form and encourage new shoots. In restoration efforts, control weeds and browsing pressure; use eco-sourced plants where possible to maintain genetic diversity. Early weed control and planting density improve establishment success.
Pests & Diseases
Good siting prevents most problems-sharp drainage and appropriate exposure are key. 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
Traditional Uses and Values
While specific traditional uses for Olearia gardneri are not widely documented, as an endemic New Zealand tree daisy, it contributes to the rich tapestry of native flora. Its conservation as a threatened species aligns with kaitiakitanga (guardianship) principles, highlighting its intrinsic value within New Zealand's unique natural heritage.
Bonus Tip
Expert Growing Advice
For optimal establishment and growth of Olearia gardneri, prioritize early and consistent weed control around young plants. Additionally, planting at an appropriate density, allowing sufficient airflow and light, significantly improves success rates, especially for this threatened species.
