Orostachys boehmeri
| Light | Bright light to full sun; more colour and tighter rosettes in strong light |
|---|---|
| Water | Moderate in growth; keep nearly dry during winter dormancy |
| Soil | Fast-draining gritty mix (see Soil and potting mix) |
| Temperature | Cold-hardy; tolerates frost and roughly USDA zones 6–9 with a dry winter |
| Propagation | Offsets on stolons; leaf and stem cuttings; seed |
| Toxicity | Non-toxic to cats and dogs |
Orostachys boehmeri is a small, cold-hardy, mat-forming succulent in the family Crassulaceae, grown for its tight blue-grey rosettes and its charming habit of sending out slender stolons tipped with new plantlets. Its rosettes taper to a rounded point and, when the plant flowers, elongate into a tall conical spike of tiny pale blooms — a shape that has earned it the common names dunce cap and Chinese dunce cap. It is one of the more approachable members of the genus Orostachys for a temperate garden or windowsill.
Description
Orostachys boehmeri forms low, congested rosettes only a few centimetres across, made up of many short, fleshy, spoon-shaped leaves in soft shades of grey-green to powdery blue, often flushed with pink or purple in strong light or cool weather. The leaves are dusted with a fine waxy bloom that gives the plant its characteristic frosted look.
The species spreads by producing thin, wiry stolons (runners) that radiate outward and end in small daughter rosettes, so a happy plant quickly builds up into a loose colony. When a mature rosette flowers it stretches upward into a slender, tapering cone densely packed with tiny star-shaped flowers, usually whitish to pale pink. As with many Orostachys, the individual rosette that flowers is typically monocarpic — it dies after blooming — but the many offsets it has produced carry the colony on.
Distribution and habitat
The species is native to Japan, where it grows on exposed rocky ground, cliff faces and thin gritty soils. Plants in habitat endure hot, bright summers and cold winters, hunkering down into tight dormant buds when conditions turn harsh. This background explains both its toughness and its need for excellent drainage in cultivation.
Cultivation
Orostachys boehmeri is an easy and forgiving succulent given the two things it insists on: sharp drainage and bright light. Grow it in a shallow pot or trough in a very free-draining, mostly mineral mix, and give it as much sun as you can — good light keeps the rosettes tight and brings out the pink and purple tints, while too little light stretches them and washes out the colour.
Water moderately through the growing season, letting the mix dry between drinks, and then keep the plant nearly dry through winter. It is genuinely cold-hardy and can be grown outdoors year-round in many temperate gardens, where a cold, dry winter rest actually suits it; the main danger is not frost but wet, poorly drained soil in cold weather. Its low, spreading habit makes it a natural for rock gardens, crevices, hypertufa troughs and shallow bowls. See Watering and Repotting for general technique.
Propagation
This is one of the simplest succulents to increase. The stolon-borne offsets can be detached once they have a few roots and potted up individually — see Propagation — offsets. Stem and even individual leaf cuttings will also root readily on a barely-moist gritty surface (see Propagation — cuttings), and the plant can be grown from seed as well, though vegetative methods are faster and keep the parent's form.
Common problems
- Rot — the usual cause of loss, almost always from a wet, slow-draining mix, especially over a cold winter; keep the plant dry when dormant.
- Etiolation — in weak light the rosettes loosen, pale and stretch, losing their compact frosted look.
- Post-flowering dieback — a flowering rosette is monocarpic and will die after blooming; this is normal, and the surrounding offsets continue the colony.
- Pests — mealybugs (white fluff tucked between the leaves) and aphids on the flower spikes are the most likely visitors. See Pests and diseases.
See also
- Orostachys — the genus overview
- Soil and potting mix · Watering · Propagation — offsets · Propagation — cuttings · Repotting