Haworthia retusa (L.) Duval
Star Cactus Haworthia
Haworthia retusa, the 'Star Haworthia', is a star-shaped rosette succulent native to the Eastern Cape of South Africa, characterized by its triangular leaves with retuse, translucent-windowed tips that give it a uniquely crystalline appearance. Its 8–12 cm rosettes form slow, elegant clusters that stand out in rare succulent collections. Like other windowed haworthias, it evolved to capture sunlight through its tips while remaining partially buried in arid soils.
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Overview
| Category | Classification |
|---|---|
| Family | Asphodelaceae |
| Genus | Haworthia |
| Growth Habit | Acaulescent star-shaped rosette with 5–7 points; slow growth, forms clumps via basal and lateral offsets. |
| Conservation Status | Not globally threatened. Widely cultivated in specialist nurseries; wild populations are protected in Eastern Cape reserves. |
| pH Target | 6.0 – 7.0 |
| Type | Very porous mineral mix: 40% cactus soil + 40% perlite + 20% coarse quartz sand. Avoid peat. |
Origin & Habitat
Morphology
Triangular leaves, 3–6 cm, thick and firm, medium to dark green, with a flat retuse apex and a translucent window traversed by dark green lines ('veins'). Upper surface slightly concave.
ecoWhite to cream tubular flowers with greenish lines, on erect scapes 20–35 cm. Sporadic flowering throughout the year, more frequent in summer.
ecoPractically absent; the rosette emerges at substrate level from a short, compact rhizome.
ecoFleshy, whitish roots with water and nutrient reserves. Sensitive to rot if drainage is poor.
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Requirements
Soil & Substrate
Type
Very porous mineral mix: 40% cactus soil + 40% perlite + 20% coarse quartz sand. Avoid peat.
groups Beneficial Associations
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Propagation Strategy
- 1 Remove the plant from the pot in spring and expose the root system.
- 2 Separate offsets with their own roots using fingers or a sterilized blade.
- 3 Let cuts dry for 2 days and plant in a small pot with very porous substrate.
- 4 Water for the first time after 7 days, very lightly.
- 1 Sow fresh seeds on the surface of moist fine mineral substrate under a transparent cover.
- 2 Maintain 20–24 °C and constant indirect light; germination in 2–6 weeks.
- 3 Gradually remove cover after a month; transplant the following year when seedlings reach 2–3 cm.
- 4 Avoid overwatering throughout; seedlings are very susceptible to damping-off.
Place in a north- or east-facing window where it receives diffuse light all day without direct exposure.
Exposure to direct sun that irreversibly damages or destroys the translucent windows.
Every 3–4 years in spring; repot only when visibly root-bound.
Quarter-strength succulent fertilizer once in spring; none for the rest of the year.
Uses & Applications
Precautions / Toxicity
Non-toxic to humans, dogs, and cats. Completely safe in the home.
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Plant Health
Mealybugs: inspect the tight interior of the rosette regularly; treat with isopropyl alcohol or systemic insecticide at reduced dose.
Root rot from excess moisture; fleshy roots rot quickly; first visible sign is softening of basal leaves.
Thrips (Frankliniella spp.) in summer; cause silvery scraping on leaf surfaces; treat with contact insecticide or neem oil.
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"The dark lines traversing the windows of H. retusa are 'veins' of chlorophyll-bearing tissue acting as optical guides, distributing light captured by the window throughout the mesophyll; this system is analogous to fiber optics and illustrates the evolutionary efficiency of plants in extreme light environments."
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Sources
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Discussion
Disclaimer
This species record is provided for educational and informational purposes only. Jardín Roca Negra does not guarantee the accuracy or completeness of the data. Content is community-curated and may be subject to revision; it should not replace advice from a qualified botanist. This species may be toxic, invasive, or subject to legal restrictions — verify before handling or cultivating. Jardín Roca Negra accepts no liability for any harm arising from reliance on this information. Images are reproduced under Creative Commons or equivalent free licenses; credits are noted below each image.