Sempervivum tectorum: the succulent that belongs outside all winter
Houseleek is the exception to almost every rule in this collection. It is fully hardy to about −30 °C, it grows through winter, and it wants more light than any Echeveria. Grown indoors it is reliably disappointing; grown on a wall it is spectacular.
Why indoor culture fails this plant
S. tectorum needs 40,000–80,000 lux to keep its form. It is also winter-active, meaning it expects a cold season with light and air movement. A 15 °C indoor windowsill in January provides neither: the rosette opens wide, the leaves lengthen, and by March it is a flat green star that never fully recovers.
The plant also has a strong cold requirement for its best colour. Red and purple tips develop reliably only after four to six weeks below 5 °C, which is why pots on an outdoor wall outperform anything under glass. If you have no outdoor space, this is not the genus to choose.
Ground versus pot: the drainage difference
In free-draining ground, houseleek survives −30 °C because the crown stays dry. In a pot the same plant dies at −8 °C, not from the cold but from ice forming in saturated compost around the crown. The distinction is entirely about water, not insulation.
For containers, use a loam-based compost with 50 % grit by volume and raise the pot on feet so it never sits in a saucer of meltwater. In a wet winter climate, an overhead shelter from November to March matters more than any fleece.
Handling the chick explosion
From May to September a mature rosette produces 8–20 chicks on stolons in every direction. Left alone, the clump becomes a dense mat and the chicks compete with the mother for light; the mother shrinks and the whole clump loses its shape.
The rule that keeps a clump looking intentional: remove every chick whose stolon has been cut naturally or that has reached 2 cm, but keep at most five per clump and space them around the perimeter. Remove stolons with a sharp pull at the base rather than cutting, so the mother's tissue closes cleanly.
Monocarpic flowering and how to plan around it
Each rosette flowers once and then dies. A rosette typically flowers in its third or fourth summer, sending up a 20–30 cm stem with pink-purple star flowers in July. When you see the stem, that rosette is finished — it will not offset again.
Plan for it. Keep three or more generations in a clump by allowing some chicks to stay and mature in place. A clump with only one large rosette left after flowering will be a bare patch for two seasons; a clump with six rosettes in mixed sizes never shows the gap.
Parameter table
- Latin name
- Sempervivum tectorum
- Common name
- Common houseleek
- Rosette form
- tight
- Light range
- 40,000–80,000 lux
- Water interval
- 12 days at 24–28 °C
- Rest period
- Fully hardy and winter-active; the rosettes contract to tight buds below 0 °C and reopen in March
- Hardiness
- 4–9 (survives −30 °C in free-draining ground)
- Offset behaviour
- Very free — stolons in every direction from May to September, 8–20 chicks a season
- Soil mix (by volume)
- 1 pumice : 1 grit : 1 loam-based potting compost, by volume
- Mature diameter
- 12 cm
| Month | State | What the plant wants |
|---|---|---|
| January | Rest | Out of action for this genus — no water unless the plant visibly shrinks, and no repotting. |
| February | Rest | Out of action for this genus — no water unless the plant visibly shrinks, and no repotting. |
| March | Growth | Repotting window opens for summer growers. Trim roots, refresh the mineral fraction, dry for a week. |
| April | Growth | Growth restarts. First full watering at the rim, then resume the published interval. |
| May | Growth | Peak growth and the offset season. Feed at quarter strength every third watering. |
| June | Growth | Lengthening days, rising heat. Watch the leaf turgor test rather than the calendar. |
| July | Growth | Hottest weeks. Water in the evening, a third of the spring volume, and only on a visible symptom. |
| August | Growth | Heat eases at night. Prepare mix and pots for the autumn repotting window. |
| September | Growth | Autumn window for winter growers. Root-prune and repot while the soil is still warm. |
| October | Growth | Peak autumn growth. This is the season when most colour work should be done. |
| November | Growth | Daylight falls fast. Taper watering by a quarter and stop feeding entirely. |
| December | Rest | Out of action for this genus — no water unless the plant visibly shrinks, and no repotting. |
Tinted rows are the months this genus is genuinely out of action: no repotting, no feeding, and water only if the plant visibly shrinks.
Four things to take away
- Hardy to −30 °C in the ground but only −8 °C in a saturated pot — drainage decides.
- Needs 40,000–80,000 lux; indoors it always stretches and never recovers.
- Best colour needs four to six weeks below 5 °C.
- Every rosette is monocarpic: keep three generations in a clump.
Informational only — This page is a cultivation record, not horticultural or plant-pathology advice. Any treatment should follow the product label and local regulation.