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Sempervivum arachnoideum

Common name: Cobweb houseleek · Cobweb hens and chicks

Sempervivum arachnoideum is a small evergreen succulent native to the Alps, Apennines, Pyrenees, and Carpathians of southern and central Europe. Its tight rosettes of red-tipped leaves are covered in fine white hairs that stretch like a cobweb across the leaf tips, giving the plant its common name. In summer, mature rosettes produce short stalks of starry pinkish-red flowers, after which the rosette dies and is replaced by its many offsets. It is prized in rock gardens, troughs, and green roofs for its distinctive webbed look.

Fun facts

  • The white hairs forming the "cobweb" help shield the rosette from intense alpine sun and reduce water loss.
  • The epithet "arachnoideum" comes from the Greek for "spider", referring to the web-like hairs.
  • It grows wild on rocky ledges and screes in the mountains, often rooting in cracks with almost no soil.
  • Like other sempervivums, the flowering rosette dies after blooming, but each plant leaves behind numerous chicks.

Care summary

Sun Full sun to light shade
Water Low; very drought tolerant, keep dry in winter
Soil Gritty, poor, sharply drained soil
Hardiness Zones 4–8
Mature height About 8–10 cm (0.25–0.3 ft)
Pet safe Yes, non-toxic to cats and dogs
Difficulty Easy
Propagation Propagate by the offsets (chicks) each rosette produces on short stolons: detach them once they reach a reasonable size, let the break dry briefly, and set them on gritty soil where they root quickly. This is essential since each rosette dies after flowering.

Make your own Cobweb houseleek · Cobweb hens and chicks profile

Common problems

    • Plant in gritty, fast-draining soil
    • Let soil dry fully between waterings
    • Avoid wetting the rosette centers
    • Remove and discard rotted rosettes
    • Move plants into full sun
    • Provide at least six hours of light
    • Reduce watering on stretched growth
    • Blast pests off with water
    • Dab mealybugs with rubbing alcohol
    • Isolate infested plants promptly
    • Improve airflow around the plants
    • Remove and destroy spotted leaves
    • Avoid overhead watering