Astroloba bullulata
| Light | Bright, indirect light to a little gentle direct sun; avoid harsh midday exposure |
|---|---|
| Water | Sparingly; let the soil dry fully between waterings, keep dry in winter |
| Soil | Gritty, fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Keep above freezing; frost-tender, roughly USDA zones 9b–11 |
| Propagation | Offsets and seed |
| Toxicity | Generally regarded as non-toxic to cats and dogs |
Astroloba bullulata is a slow-growing South African succulent of the genus Astroloba, forming neat columns of tightly stacked, triangular leaves. It is named for the small raised tubercles that roughen the surfaces of its leaves, giving each column a finely bumpy, pebbled texture rather than the smooth faces seen in some other species.
Description
Astroloba bullulata grows as an erect to slightly leaning column of densely overlapping, deltoid (triangular) leaves arranged in spiralling ranks. The leaves are firm and dark green, often flushed reddish or olive, and their outer surfaces are covered in low, rounded tubercles — the "little blisters" (bullulae) that give the species its name — creating a distinctly roughened, warty texture; the tubercles and leaf margins can flush pink to whitish in strong sun. Individual columns are modest in size (to roughly 30 cm tall), and established plants slowly offset from the base to build up small clustering clumps over time.
Like other members of the genus, it produces a slender inflorescence bearing small tubular flowers with yellowish, star-tipped tepals. The blooms are unshowy compared with the foliage; this is a plant grown above all for the geometry and texture of its stacked leaves.
Distribution and habitat
The genus Astroloba is endemic to South Africa, and A. bullulata occurs in the arid interior of the Western Cape and the adjoining Northern Cape — roughly the Ceres Karoo, Sutherland (Roggeveld) and Laingsburg districts — in succulent karoo and karroid scrub. Plants grow on rocky slopes, often in clay-rich soils and tucked among stones or low shrubs that give a little shade and shelter through the hottest, driest part of the year. Rainfall is low and falls mainly in winter, and the plants are well adapted to long dry spells.
Cultivation
Astroloba bullulata is an undemanding but slow plant that rewards restraint. Grow it in a very free-draining, mostly mineral mix in a pot only a little larger than the plant, and give it bright light — indirect light with some gentle direct sun brings out the best colour and keeps the columns compact, while too little light causes stretching. Protect it from harsh midday summer sun, which can scorch the leaf surfaces.
Water thoroughly only once the soil has dried right through, then wait; the tubercled leaves store enough moisture to carry the plant through dry periods, and overwatering is the quickest way to lose it. Keep the plant nearly dry and cool through winter. Astrolobas are frost-tender, so grow it under cover or bring it indoors where freezes occur. See Watering and Repotting for general technique.
Propagation
The easiest method is to remove rooted offsets from around the base of a clustering plant, allow the cut surface to callus for a few days, and pot them into the same gritty mix. See Propagation — offsets for a full walkthrough. The species can also be raised from seed, though germination and growth are slow; because Astroloba species hybridise readily, seed from mixed collections may not come true. See Propagation — seed.
Common problems
- Rot — almost always from overwatering or a slow-draining mix; the base or lower leaves soften and discolour.
- Etiolation — too little light causes the leaves to space out and the column to stretch and lean, losing its tight, symmetrical stacking.
- Pests — mealybugs (white fluff nestled between the overlapping leaves) and root mealybugs are the usual troubles; watch for them where leaves meet the stem. See Pests and diseases.
See also
- Astroloba — the genus overview
- Soil and potting mix · Watering · Repotting
- Propagation — offsets · Propagation — seed