Sempervivum tectorum
| Light | Full sun to bright light; tolerates some light shade |
|---|---|
| Water | Sparingly; drought-tolerant, let the soil dry between waterings |
| Soil | Gritty, fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Fully cold-hardy; survives hard frost, roughly USDA zones 3–8 |
| Propagation | Offsets (the primary method); also seed |
| Toxicity | Non-toxic to cats and dogs |
Sempervivum tectorum, the common houseleek, is a hardy, mat-forming succulent from the mountains of southern and central Europe that produces tight rosettes of fleshy, often red-tipped leaves. Long grown on cottage roofs and walls — the species name tectorum means "of roofs" — it is one of the toughest and most beginner-friendly succulents you can grow, thriving outdoors through frost and drought where tender plants would fail. It is the classic member of the genus Sempervivum, the "hens and chicks."
Description
Sempervivum tectorum forms a flattened, symmetrical rosette 5–12 cm across, composed of many thick, pointed leaves. The leaves are green and typically flushed with red or purple toward their tips, and their margins are edged with fine hairs (cilia). Each rosette spreads by sending out short stolons that end in smaller daughter rosettes clustered around the parent — the origin of the affectionate common name hens and chicks.
Individual rosettes are monocarpic: after several years a mature rosette elongates into a stout flowering stem carrying a cluster of star-shaped, dull reddish-purple flowers in summer. That rosette then dies, but the ring of offsets it leaves behind carries the colony on indefinitely, so a healthy clump is effectively immortal.
Distribution and habitat
The species is native to the mountains of southern and central Europe, including the Alps, Pyrenees and Apennines, where it grows on rocky slopes, cliff faces and thin, gritty soils. It is adapted to bright sun, sharp drainage and wide swings of temperature, and its low, water-storing rosettes shrug off both drought and hard winter cold. Centuries of cultivation across Europe — famously planted on thatched and tiled roofs, once believed to guard a house against lightning — have blurred its exact wild range.
Cultivation
Sempervivum tectorum is about as forgiving as a succulent gets, provided it has sun and drainage. Grow it in a gritty, free-draining mix in a shallow pot, trough or rockery, in full sun to bright light; too much shade makes rosettes loosen, stretch and lose their red colouring. Water only when the soil has dried, and much less in winter — the plant is far more likely to be killed by wet, stagnant soil than by cold.
Being fully hardy, it is ideal for unheated outdoor culture, alpine troughs, wall crevices and green (living) roofs, and needs no winter protection beyond good drainage. See Watering and Repotting for general technique; lift and divide crowded clumps every few years to keep them vigorous.
Propagation
Propagation could hardly be simpler. The plant multiplies itself through offsets, and these are removed and rooted with almost no effort: detach a daughter rosette, ideally with a short length of stolon or a few roots, settle it onto gritty soil and keep it lightly moist until established. This is the standard and most reliable method — see Propagation — offsets.
The species can also be raised from seed, though seed-grown plants are variable and slower, so named forms are always increased vegetatively to stay true.
Cultivars
Sempervivum has been bred extensively, and S. tectorum sits behind or alongside a great many garden selections and hybrids prized for leaf colour and rosette form. Named forms range from deep wine-red and purple through frosted silvery-blue to heavily "cobwebbed" rosettes veiled in white hairs. Colour is strongly light- and season-dependent, intensifying in bright sun and cool weather. See the Sempervivum genus page for an overview of the cultivar groups.
Common problems
- Rot — the main cause of loss, almost always from soggy, poorly drained soil or overwatering, especially over winter.
- Etiolation — too little light makes rosettes open up, stretch and fade to plain green.
- Pests — generally trouble-free, but watch for mealybugs (white fluff between the leaves), vine weevil grubs at the roots, and aphids on flower stems. See Pests and diseases.
See also
- Sempervivum — the genus overview
- Propagation — offsets · Soil and potting mix · Watering · Repotting