Cobweb houseleek
Sources last read 14 September 2026.
Not yet rated How forgiving it is has not been judged here yet.
Also called cobweb sedum.
Toxicity is partly unassessed
- Not assessed for cats. This plant is not on the ASPCA list. That is not a finding of safety: none of the sources read for this site gives an answer either way. Treat it as unknown.
- Not assessed for dogs. This plant is not on the ASPCA list. That is not a finding of safety: none of the sources read for this site gives an answer either way. Treat it as unknown.
- Not assessed for people. RHS publishes no harm statement for this plant. That is not a finding of safety: none of the sources read for this site gives an answer either way. Treat it as unknown.
What the sources say about its care
Sources file this plant under other names: Sempervivum arachnoideum AGM. Citations below point at the name its source uses.
- Light
- Full sunRHS · read 13 September 2026
- Water
- Well-drainedRHS · read 13 September 2026
- Humidity
No source read publishes a humidity figure for any plant on this site. What follows is general guidance for foliage plants.
Most foliage plants prefer more humidity than a heated room gives; succulents are named as an exceptionPenn State Extension · read 13 September 2026- Temperature
How cold this tolerates, not what it prefers. No source read for this site publishes a preferred range for a plant indoors.
H7 — colder than -20°CRHS · read 13 September 2026- Soil
- Loam, Sand; pH Acid or Alkaline or NeutralRHS · read 13 September 2026
- Toxic to cats
- Not on the ASPCA list. That is not a finding of safety.ASPCA · read 13 September 2026
- Toxic to dogs
- Not on the ASPCA list. That is not a finding of safety.ASPCA · read 13 September 2026
- Harmful to people
- No statement of harm to people is published for this plant; that absence is not evidence it is safe.RHS · read 13 September 2026
Routine care
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Photographs
About the plant
Sempervivum arachnoideum, the cobweb house-leek, is a species of flowering plant in the family Crassulaceae, native to European mountains, in the Alps, Apennines and Carpathians. Growing to 8 cm (3 in) tall by 30 cm (12 in) wide, it is a rosette-forming succulent perennial, valued in cultivation for its ability to colonise hot, dry areas via offsets.
From Wikipedia, CC BY-SA 4.0 · read 13 September 2026
- Native range
- N. Spain to Alps and AppenniniWorld Checklist of Vascular Plants, June 2026 release, CC BY.Kew WCVP · read 13 September 2026Pyrenees to Carpath.RHS · read 13 September 2026
- Climate
- temperateWorld Checklist of Vascular Plants, June 2026 release, CC BY.Kew WCVP · read 13 September 2026
- Growth form
- succulent perennialWorld Checklist of Vascular Plants, June 2026 release, CC BY.Kew WCVP · read 13 September 2026Matforming (evergreen)RHS · read 13 September 2026
- Size
- Height Up to 10 cm; spread 0.1-0.5 metres after 5–10 yearsRHS · read 13 September 2026
- Flowering
- Flowers pink in summerRHS · read 13 September 2026
Other Sempervivum
More of the Crassulaceae family
Burro's tailLeaves soften and curl inward
Flaming KatyA thin dry rim that crumbles between the fingers
Jade plantPale dry areas across the upper leaves only
Mexican snowballPale dry areas across the upper leaves only
Aeonium haworthiiSourced care, difficulty not yet judged
Aeonium undulatumSourced care, difficulty not yet judged
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Sources
- ASPCA · read 13 September 2026
- Kew WCVP · read 13 September 2026
- Penn State Extension · read 13 September 2026
- RHS · read 13 September 2026
- Wikipedia · read 13 September 2026
What this does not cover
The figures above are what published sources say, not measurements of the plant in your room. They say nothing about your pot size, your water, the season, or how far from the glass the plant stands, and those decide more than any figure here does.
Humidity has no species figure because no source read for this site publishes one, and the only temperature published for this plant is a cold floor. The simulator fills those gaps with general figures for its kind of plant, marked as general and listed on how we read sources. Where a toxicity row says the plant was not assessed, that is the absence of a finding and not a finding of safety.
If something is already wrong, the diagnosis tool asks about the soil, the window and the watering, which is where the answer usually is.