Haworthiopsis nigra
| Light | Bright, indirect light; avoid harsh midday sun which scorches the dark leaves |
|---|---|
| Water | Sparingly; let the soil dry fully between waterings, near-dry in winter |
| Soil | Gritty, fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Frost-tender; keep above about 5 °C, USDA zones 10–11 |
| Propagation | Offsets (division); seed |
| Toxicity | Non-toxic to cats and dogs |
Haworthiopsis nigra is a small, slow-growing South African succulent named for its strikingly dark colouring — the leaves range from deep olive to an almost black brown-green, their rough surfaces packed with dense, raised tubercles. The stubby, pointed leaves are arranged in three neat vertical ranks (a three-ranked or tristichous habit), giving the plant a distinctive angular, columnar silhouette quite unlike the softer rosettes of many relatives. It belongs to the genus Haworthiopsis, the firm-leaved haworthias split off from the old genus Haworthia.
Description
Haworthiopsis nigra forms compact clumps of small, erect columns. Each stem is built from short, thick, incurved leaves that spiral in three distinct ranks up the stem, so the plant looks tightly stacked and three-sided rather than flat. Individual columns are usually only a few centimetres across, and clusters slowly build up over years as the plant offsets from the base.
The leaves are the plant's signature feature: hard, rigid and roughened all over with prominent dark tubercles — small raised bumps that catch the light and give the surface a pebbly, warty texture. Colour ranges from dusky green to a deep blackish brown, intensifying under bright light and cooler, drier conditions to the near-black tone that gives the species its name. Small, tubular whitish flowers on a slender stalk appear in the warmer months, typical of the genus and unremarkable next to the foliage.
Distribution and habitat
The species is native to the semi-arid Karoo of the Eastern Cape, South Africa, where it grows among rocks and in the shelter of low shrubs and grasses on stony ground. In habitat the dark, tuberculate leaves help the plant blend into gritty soils and rock crevices, and the shade of surrounding vegetation protects it from the fiercest sun. Like most firm-leaved haworthias it is adapted to a dry climate with occasional rain, enduring long dry spells by drawing down and staying compact.
Cultivation
Haworthiopsis nigra is an undemanding but slow houseplant, well suited to a bright windowsill. Give it bright, indirect light — enough to keep the leaves dark and tight, but with protection from scorching midday sun, which can bleach or burn the near-black surfaces. Grow it in a gritty, free-draining mineral mix in a snug pot.
Water thoroughly only once the soil has dried right through, then let it dry again; in winter keep the plant nearly dry and cool to give it a proper rest. As with all haworthiopsis, overwatering and soggy soil are the main killers, causing the roots and base to rot. The species' natural slowness means it rarely needs repotting more than every few years. See Watering for general technique.
Propagation
The easiest method is division: mature clumps produce offsets (pups) at the base that can be teased away with a few roots and potted individually. Unlike soft-leaved succulents, the hard leaves of haworthiopsis seldom root from leaf cuttings, so division and seed are the practical routes. Seed is possible where flowers are hand-pollinated, but is a patient grower's route given the species' pace. Let cut or detached surfaces dry before planting to reduce the risk of rot.
Common problems
- Rot — the usual cause of loss, almost always from overwatering or a slow-draining mix; the base and roots soften and blacken.
- Scorch and bleaching — too much direct sun fades or burns the dark leaves; move to brighter shade if the colour washes out.
- Etiolation — too little light stretches the stems and loosens the tidy three-ranked stacking.
- Pests — mealybugs (white fluff tucked between the leaves and at the roots) are the most common; watch also for root mealybugs.
See also
- Haworthiopsis — the genus overview
- Soil and potting mix · Watering · Repotting
- Propagation — offsets · Propagation — cuttings · Propagation — seed
- Pests and diseases