NZ Harebell
Wahlenbergia albomarginata
The NZ Harebell (scientific name: Wahlenbergia albomarginata ) is a charming and delicate perennial herb endemic to New Zealand. Found across the South Island and Stewart Island, it is beloved for its nodding, bell-shaped flowers that range from pure white to a soft, ethereal blue. This rhizomatous plant forms low-growing mats, making it an excellent choice for rock gardens and alpine-themed plantings. This guide explores its unique botanical features, its natural habitat in New Zealand's high country, and how to successfully cultivate this resilient native beauty in Ground Cover .
Plant Description
Wahlenbergia albomarginata is a small, mat-forming perennial herb that spreads via a slender underground rhizome system. It typically reaches a height of 5 to 20 centimetres when in flower, with a spread of 25 to 40 centimetres. The evergreen foliage consists of small, spatula-shaped (obovate) leaves, 10 to 40 millimetres long, which often form attractive rose-like clusters at the tips of the branches. A distinctive feature of this species is the thickened, white margin often found on the leaf edges, which is reflected in its scientific name "albomarginata." The flowers are solitary, bell-shaped, and measure 10 to 20 millimetres in length. They range in colour from white to pale blue, often with darker blue veins or edges. The flowering season is quite long, stretching from November through to April, providing a continuous display of delicate blooms.
Quick Facts
| Scientific Name | Wahlenbergia albomarginata |
|---|---|
| Height | 5-20 centimetres |
| Spread | 25-40 centimetres |
| Water Needs | Moderate (Well-drained) |
| Light | Full Sun to Partial Shade |
| Frost Tolerance | High (Fully hardy) |
| Salt Tolerance | Moderate |
| Growth Rate | Medium |
| Lifespan | Up to 15 years |
Climate Best Suited to
The NZ Harebell is a hardy species well-adapted to the temperate and sub-alpine climates of the South Island. It prefers moderate temperatures, ideally between 5°C and 25°C, and is fully frost-tolerant. While it can handle the intense sunlight of high altitudes, it performs best when its root zone is kept cool and moist. In warmer northern regions, it should be grown in a spot that receives morning sun but is protected from the harsh afternoon heat.
Regional Suitability
| City | Climate Suitability |
|---|---|
| Auckland | Moderate (Requires cooling) |
| Wellington | Good |
| Christchurch | Excellent |
| Dunedin | Excellent |
| Invercargill | Excellent |
Plant Habitat
Naturally occurring across the inland east coast of the South Island and Stewart Island, Wahlenbergia albomarginata is a versatile plant of the high country. It is commonly found in dry, lowland tussock-grasslands, on river terraces, and amongst rocky outcrops. Its range extends into the sub-alpine zone, where it can be found at altitudes up to 1700 metres. It thrives in well-draining, often stony or sandy soils, frequently growing in the short turf near riverside margins or in stable scree.
Plant Conservation
Wahlenbergia albomarginata is currently classified as "Not Threatened." It is a relatively common species within its range. However, certain subspecies, such as W. albomarginata subsp. flexilis , are considered "Naturally Uncommon" and have a narrower geographic range. These specific populations can be vulnerable to habitat modification and browsing by livestock such as sheep and goats, as well as feral animals like rabbits and hares. General conservation of tussock-grassland habitats is key to the long-term success of this species.
Growing Requirements
Soil Requirements
Requires excellent drainage and good aeration. Prefers mineral-rich, gritty soils.
- Well-drained gritty or sandy soil
- pH between 6.0 and 7.0
- Does not tolerate heavy clay
Light Requirements
Thrives in full sun but tolerates partial shade. Full sun encourages more flowers.
- Best in full sun
- Dappled shade acceptable
- Protection from midday heat in North
Water Requirements
Needs consistent moisture but must never sit in water. Drought tolerant once established.
- Weekly watering at the base
- Keep roots cool with mulch
- Avoid waterlogging
Planting Guide
When planting NZ Harebell, choose a sunny, well-draining spot such as a rockery, the edge of a garden path, or a raised bed. Incorporate fine grit or sharp sand into the planting hole to ensure drainage. If planting from a pot, tease out the rhizomes gently to encourage them to spread into the surrounding soil. Space plants about 20 to 30 centimetres apart to allow the mat to fill in. A layer of fine gravel mulch is highly recommended; it keeps the leaves clean, suppresses weeds, and reflects light back into the plant while keeping the roots cool.
Ecological Role
In its natural tussock-grassland habitat, Wahlenbergia albomarginata plays an important role as a colonizer of open, gritty ground. Its rhizomatous habit helps to bind loose soil and fine scree. The flowers are a significant source of nectar for specialized indigenous insect pollinators, including native bees and flies. Because the plant relies on these specific insects for cross-pollination, it is a vital part of the complex web of life in the South Island high country. Its presence contributes to the rich floral diversity of the alpine and sub-alpine zones.
Uses & Significance
Garden Uses
A delightful addition to any garden looking for a touch of mountain charm.
- Perfect for rock gardens and scree beds
- Excellent edging plant for sunny paths
- Beautiful in troughs or shallow containers
Recognized as one of the iconic "bells" of the New Zealand landscape.
- Symbolic of the South Island high country
- A classic subject for New Zealand botanical art
- Highly valued by alpine plant societies
Ecological Value
Supports the biodiversity of New Zealand's unique mountain ecosystems.
- Nectar source for native bees and flies
- Soil-binding rhizomatous growth habit
- Indicator of healthy tussock-grassland systems
Cultural Significance
While specific records are limited for this species, Wahlenbergia albomarginata sits within a wider native plant tradition valued for its ecological role and local stewardship.
Landscaping Uses
In landscaping, the NZ Harebell is used to create soft, textural interest at ground level. Its delicate blue and white flowers provide a beautiful contrast to the bold, architectural forms of native speargrasses (Aciphylla) or the golden hues of tussocks (Chionochloa). It is particularly effective when used in mass plantings to form a flowery carpet or when tucked into crevices between large landscape rocks. Because of its low height and spreading habit, it works well as a living mulch in specialized alpine gardens.
Seasonal Care Calendar
Spring
Growth resumes and the first flower buds appear.
- Apply a balanced slow-release fertiliser
- Check for any invasive weeds in the mat
- Ensure consistent moisture as growth starts
Summer
The peak flowering period.
- Deadhead spent flowers to prolong blooming
- Provide extra water during dry spells
- Maintain a cool root zone with grit mulch
Autumn
Flowering winds down and seeds ripen.
- Collect fresh seeds for propagation
- Reduce watering as the plant slows down
- Tidy up any brown or damaged foliage
Winter
The plant enters dormancy.
- Protect from excessive winter wetness
- Ensure the site remains free-draining
- Plant is fully frost hardy; no cover needed
When to Prune and How Much
Wahlenbergia albomarginata requires very little actual pruning, but regular grooming is beneficial.
- Deadhead throughout summer to encourage more flowers
- Trim back the edges of the mat if it overgrows its space
- Lightly shear the plant after flowering to maintain a compact habit
The best time for a light tidy-up is in late autumn after the main flowering flush has ended. This helps the plant stay tight and "rose-like" rather than becoming leggy. Avoid heavy pruning into the main root system.
How to Grow NZ Harebell ( Wahlenbergia albomarginata )
Growing the NZ Harebell ( Wahlenbergia albomarginata ) is a rewarding experience, as it brings a touch of the Southern Alps into your garden. To succeed, you must focus on the foundations: drainage and light. This plant will not tolerate "wet feet," so ensuring your soil is gritty and free-draining is paramount. While it is a hardy mountain dweller, it appreciates a bit of care in the garden. Keeping the roots cool with a gravel or stone mulch mimics its natural environment and helps it survive the summer heat. Be patient with its spread; it moves gently through the soil via rhizomes and will eventually form a beautiful, dense carpet. Remember that while it is evergreen, it may look a bit tattered in the middle of winter, but it will bounce back quickly with the spring sun. It is a fantastic plant for a beginner alpine gardener due to its general hardiness compared to more temperamental mountain species.
From Seed
Seeds are a great way to start, especially if they are fresh. Note that cultivated plants may not always set viable seed.
- Collect ripe seed capsules in late summer or autumn.
- Sow immediately onto a well-drained, gritty seed mix.
- Lightly cover with a fine layer of grit; they need some light.
- Keep the mix moist and place in a cool, bright spot.
Fresh seeds should germinate readily in the following spring as temperatures rise.
From Cuttings
Tip cuttings are an effective and fast way to create new plants.
- Take 5cm tip cuttings in late spring or early summer.
- Dip the ends in a rooting hormone if desired.
- Insert into a mix of sharp sand and peat.
- Keep in a humid, shaded environment until roots form.
Additional Methods
Division is perhaps the easiest method for the home gardener.
- Carefully lift a section of the mat with roots and rhizomes attached.
- Best done in early spring just as growth starts.
- Replant immediately into prepared soil and water well.
Pests & Diseases
The NZ Harebell is relatively pest-resistant. The most common issue is crown rot, which occurs if the soil is too wet or the air circulation is poor. Ensure the plant is not buried by fallen leaves or other debris. Slugs and snails may occasionally graze on the young shoots in spring, so keep an eye out and use bird-friendly controls if necessary. Aphids can sometimes be found on the flower buds in early summer; they can usually be washed off with a gentle spray of water.
Bonus Tip
For a truly spectacular display, plant NZ Harebell in a terracotta alpine trough. The porous clay helps keep the roots cool and prevents waterlogging, allowing you to create a perfect miniature mountain scene on your patio or courtyard.
Related Plants
Explore other native plants that share similar characteristics or habitats with NZ Harebell ( Wahlenbergia albomarginata ), offering further insights into New Zealand's diverse flora. These related species provide context and opportunities for complementary planting in your garden.
