Haworthia arachnoidea
| Light | Bright, indirect light; protect from harsh direct summer sun |
|---|---|
| Water | Sparingly during growth; keep drier in the heat of summer and rest in winter (see Watering) |
| Soil | Gritty, free-draining mineral mix (see Soil and potting mix) |
| Temperature | Keep above freezing; USDA zones 9b–11 |
| Propagation | Offsets and seed; leaf cuttings possible but slower |
| Toxicity | Non-toxic to cats and dogs |
Haworthia arachnoidea is a small, stemless South African succulent that forms dense rosettes of soft green leaves whose margins are fringed with long, fine, translucent bristles. These pale bristles arch inward over the plant so that a well-grown rosette looks as if it has been wrapped in a delicate spider's web — the source of both its scientific name (botanical Latin arachnoideus, "cobweb-like", from Greek arachnē, "spider") and its common name, the cobweb haworthia. It is a variable, widespread member of the genus Haworthia and a longtime favourite of windowsill collectors.
Description
Haworthia arachnoidea forms compact, stemless rosettes typically 4–10 cm across, either solitary or slowly clustering into small clumps. The leaves are triangular to lance-shaped, incurving, and range from pale to deep green, often flushing reddish or bronze in bright light or under stress. What sets the species apart are the numerous slender, soft, whitish bristles (technically fine marginal teeth and hairs) that grow from the leaf edges and sometimes the keel; on many forms these are long enough to meet across the centre of the rosette and knit together into a lacy, cobweb-like veil.
The species is notably variable across its range, and several varieties have been described that differ in leaf colour, bristle length and density, and overall size. Small, tubular white flowers on a slender stalk appear mostly in the cooler part of the year but are modest — this is a plant grown for its foliage, not its bloom.
Distribution and habitat
The species is widespread across the Western and Eastern Cape of South Africa, one of the more common and broadly distributed haworthias. It grows in a range of habitats from rocky slopes to gravelly flats, often tucked among rocks, in the shelter of shrubs, or partly buried with only the leaf tips exposed. This half-buried habit and the pale bristle "veil" help shade and protect the plant from intense sun and dry heat.
Cultivation
Haworthia arachnoidea is an easygoing, rewarding grower that suits a bright windowsill or a lightly shaded spot in a greenhouse. Give it bright but filtered light: too little and the rosette stretches and loses its tight form, while unshaded midday summer sun can scorch the soft leaves and bleach the colour. A little sun stress, however, brings out attractive reddish and bronze tones.
Plant it in a gritty, mostly mineral mix in a pot with good drainage. Water thoroughly when the soil has dried out during the active growing seasons of spring and autumn, and ease right off in the heat of high summer and through winter, when many haworthias slow down or rest. Overwatering — especially in a heavy mix or a cold, dark spot — is the main cause of loss. See Watering and Repotting for general technique.
Propagation
The easiest method is division: clustering plants produce offsets that can be separated during repotting and grown on their own roots (see Propagation — offsets). The species also comes readily from seed, though seedlings are slow and, given the plant's variability, may differ from the parent (see Propagation — seed). Leaf cuttings are possible but less reliable than with some other succulents. Let any cut or torn surface callus for a few days before setting it on a barely moist mineral mix.
Common problems
- Rot — usually from overwatering, a slow-draining mix, or water sitting in the crown; the base or centre softens and browns.
- Etiolation — too little light stretches the rosette upward and opens it out, spoiling the tight, webbed form.
- Scorch — sudden intense sun on soft leaves causes bleached or brown patches; acclimatise plants gradually.
- Pests — mealybugs (white fluff between the leaves and at the roots) and, less often, root mealybugs and fungus gnats in wet soil (see Pests and diseases).
See also
- Haworthia — the genus overview
- Soil and potting mix · Watering · Repotting · Propagation — offsets · Propagation — seed