Scleranthus uniflorus
A dense, slow-growing alpine cushion plant for cool, free-draining rock and scree gardens. Requires full sun, low fertility and excellent drainage among our alpine plants. Learn more in our native plants guide.
| Scientific Name | Scleranthus uniflorus |
|---|---|
| Common Name(s) | Cushion Plant, Knawel Cushion, New Zealand Moss |
| Family | Caryophyllaceae |
| Native To | New Zealand (alpine and subalpine regions) |
| Type | Perennial herb, ground cover |
| Height | 0.03–0.05 meters (1-3 inches) |
| Spread | 0.3–0.6 meters (12-18 inches) |
| Leaves | Bright green, tiny, linear, moss-like |
| Flowers | Inconspicuous, tiny pale green to cream or greenish-white (summer) |
| Light | Full sun to partial shade |
| Soil | Well-drained, sandy, or gritty; dislikes winter wet/waterlogging |
| Water Needs | Drought-tolerant once established; benefits from occasional watering |
| Uses | Rockeries, Japanese-style gardens, between pavers, moss/lawn alternative |
| Toxicity | Non-toxic to humans and animals |
| Growth Habit | Slow, tidy growth; no mowing required |
| Frost Tolerance | Hardy once established |
| Salt Tolerance | Moderate; tolerates some coastal exposure |
| Growth Rate | Slow |
| Lifespan | Perennial |
Scleranthus uniflorus thrives in specific climate conditions, primarily requiring full sun to partial or dappled shade. While it can tolerate some shade, it tends to grow looser and taller in such conditions. It prefers well-drained, sandy, gritty, or loamy soil and dislikes winter wet or waterlogging. It is frost-hardy, typically growing in USDA Zones 6-10, but does not tolerate very hot and humid weather.
Scleranthus uniflorus is native to the alpine and subalpine regions of New Zealand. It is well-suited to cooler climates with good drainage and can tolerate frost. It is not ideal for very hot and humid environments.
| Region | Climate Suitability |
|---|---|
| Whangārei | Ideal |
| Auckland | Ideal |
| Hamilton | Ideal |
| Tauranga | Ideal |
| Rotorua | Ideal |
| Gisborne | Ideal |
| New Plymouth | Ideal |
| Napier | Ideal |
| Whanganui | Ideal |
| Palmerston North | Ideal |
| Wellington | Ideal |
| Nelson | Ideal |
| Christchurch | Ideal |
| Dunedin | Ideal |
| Invercargill | Ideal |
Scleranthus uniflorus prefers well-drained, sandy, or gritty soil. It is crucial to avoid overly wet or spongy soils, particularly during winter, as it will not tolerate waterlogging. It can also grow in average soil.
It prefers mostly sun to full sun. While it can tolerate partial shade, it may grow less compactly and become taller in shadier conditions.
Maintain even moisture, ensuring the soil does not completely dry out for extended periods. While drought-tolerant once established, it benefits from occasional watering during prolonged dry spells. When planting, it requires regular watering until established, typically around 12 weeks. A wet-dry watering cycle is recommended, avoiding soggy conditions.
Scleranthus uniflorus is primarily valued for its ornamental and landscaping uses. Its dense, moss-like perennial ground cover makes it a versatile plant for various garden settings.
In spring, Scleranthus uniflorus begins its active growth. This is an ideal time for planting new specimens or dividing clumps. Fertilize with a slow-release fertilizer if desired. Ensure consistent moisture as new growth emerges.
Summer is the peak growing season for Scleranthus uniflorus. Inconspicuous flowers may appear. Ensure consistent moisture, especially during dry spells, but avoid waterlogging. Monitor for any brown patches and treat with fungicide if necessary.
During autumn, Scleranthus uniflorus continues its evergreen display. Reduce watering as temperatures cool. Ensure good drainage to prevent winter wet issues.
Winter is generally a period of slower growth for Scleranthus uniflorus. It is frost-hardy, but ensure it is not in overly wet soil, as it dislikes winter wet. If used as a lawn alternative, mow once.
Scleranthus uniflorus generally does not require extensive pruning. Its natural growth habit is to form a dense, compact cushion.
The optimal time to plant Scleranthus uniflorus is from late spring until mid-summer, when the soil is warm and the sun is gentle.
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Water regularly until established (around 12 weeks), ensuring the soil remains moist but not waterlogged. Once established, it is drought-tolerant but benefits from occasional watering during prolonged dry spells. Avoid overwatering.
Cushion Plant (Scleranthus uniflorus) forms tight, moss-like mats in alpine and rock-garden settings. This unique New Zealand native is highly valued for its ability to create dense, evergreen cushions that are perfect for filling gaps between pavers, softening rock edges, or as a low-maintenance lawn alternative in small, dry areas. Its slow growth and compact habit make it an ideal choice for specialized garden designs. Successful cultivation depends on providing sharp drainage, cool conditions, and protection from prolonged winter wet. Understanding its propagation methods is key to successfully establishing this distinctive alpine plant.
Division of established clumps is the most reliable and commonly suggested method for propagating Scleranthus uniflorus. This is best undertaken in cool, moist weather, typically in early spring or early autumn. Carefully lift the mat gently with a broad blade or trowel, then tease apart small sections that include both living green growth and attached roots, being careful to avoid breaking the fine root network. Replant divisions immediately at the same depth into a gritty, free-draining mix, such as a blend of fine gravel, sand, and a small amount of compost. Water thoroughly to settle the soil around the roots. Keep the newly planted divisions evenly moist (never waterlogged) and shaded from hot afternoon sun until new growth indicates successful establishment. This method is particularly effective for expanding existing plantings or for rejuvenating older clumps that may show dieback in the center.
Propagating Cushion Plant from seed is possible but generally slower and less predictable than division. Sow fresh, cleaned seed in autumn or late winter onto a sterile, gritty, free-draining seed mix. Surface sow or cover very lightly with fine medium, as light can aid germination. Maintain cool temperatures (around 10–15 °C), bright but indirect light, and steady moisture with a fine mist. Germination is often irregular and can take several weeks to months. Once tiny seedlings appear, carefully prick them out with a plug of media to minimize root disturbance and grow them on in cool, well-lit conditions. Gradually harden them off before planting out. Due to the slow growth rate from seed, this method is often preferred by specialist growers or for large-scale propagation projects.
Scleranthus uniflorus is generally considered to be pest-free. However, it can be susceptible to certain diseases, primarily related to improper growing conditions.
Maintaining proper growing conditions, especially well-drained soil and appropriate watering, is key to preventing most issues with Scleranthus uniflorus.
Scleranthus uniflorus, often called New Zealand Moss, is a fantastic choice for creating a unique, low-maintenance, and evergreen groundcover. Its dense, cushion-like growth and vibrant lime-green color make it an excellent alternative to traditional moss in Japanese-style gardens or between flagstones. It's also remarkably tough, tolerating light foot traffic and generally being pest and disease-free, making it a resilient and beautiful addition to alpine or rock gardens.
Explore other plants that are related to Scleranthus uniflorus, either within the same genus or the wider Caryophyllaceae family, offering further insights into its botanical connections and similar garden uses.
Scleranthus biflorus - Another species within the same genus, also forming dense, cushion-like mats, often with a brighter lime-green color.
Learn more
Dianthus caryophyllus - A well-known ornamental flower belonging to the same family (Caryophyllaceae), showcasing the diverse forms within the family.
Learn more
Sagina subulata 'Aurea' - While not directly related, it is often compared to Scleranthus uniflorus due to its similar moss-like appearance and use as a groundcover.
Learn moreUnderstanding the natural habitat of Cushion Plant provides essential guidance for successful cultivation.
The ecological adaptations of Cushion Plant reveal remarkable specialization to extreme alpine conditions.
While not currently threatened, Cushion Plant faces potential pressures from climate change and habitat modification.
Specialized cultivation techniques for optimal performance in non-alpine environments.
Cushion Plant offers unique design opportunities for specialized garden situations requiring low-maintenance groundcover.
In its native alpine environment, Cushion Plant plays important ecological roles and supports specialized alpine ecosystems.
A dense, slow-growing alpine cushion plant for cool, free-draining rock and scree gardens. Requires full sun, low fertility and excellent drainage among our alpine plants.
Successful establishment of Cushion Plant requires careful attention to drainage and gradual acclimatization to garden conditions.
Cushion Plant (Scleranthus uniflorus) holds cultural importance in Aotearoa New Zealand through its roles in traditional knowledge and native ecosystems.