Species · genus Sempervivum · Crassulaceae

Cobweb House-leek

Sempervivum arachnoideum L.

Also known as: Cobweb Houseleek

Growth habit

succulent perennial

Native range

Austria, Corse, France, Germany, Italy, Spain, Switzerland

Reference · S. arachnoideum

Cultivars of S. arachnoideum

The named forms growers keep — each with its own page, each honest about how much we know.

No named cultivars catalogued under S. arachnoideum yet. When growers document a stable, named form, it earns its own page here.

Guide

The species-level account. Cultivar pages build on this and say where they differ.

Sempervivum arachnoideum is an alpine succulent from the rocky slopes of central and southern Europe, forming tight cobwebbed rosettes that store water in their leaves. It wants gritty, fast-draining mix, strong direct light, and cool airflow, and rots quickly if left damp. Water deeply only once the soil has dried completely through the pot, then let it dry again.

Care recipe

The species record — the baseline every cultivar inherits unless it says otherwise.

Care notes are early — not yet verified

Light: ai:claude-opus-4-8
Water: ai:claude-opus-4-8 (range 10-21d)
Humidity: ai:claude-opus-4-8
Soil: ai:claude-fable-5
Care: ai:claude-fable-5

Light

Direct sun

Water

≈ every 21 days

Humidity

Low — average room

Temperature

4–24 °C

Soil mix

Very gritty, sharply draining alpine succulent mix

Propagation

Offsets — the cobweb rosettes pup freely and root where they land

Fertilizing

Little to none — a weak feed once a year at most

Growth rate

Slow

Flowering

Rosy-red star flowers once, then that rosette dies after setting offsets

ToxicityAuthoritative · species

Not yet documented

This is where toxicity lives — every cultivar of this species inherits it and none can override it.

Reference images

Every image credited. Licenses link to their deeds.

No reference gallery yet

A few clear photos — habit, a mature leaf, a flower if it blooms — would give this page its eyes.

Add images

Sources: ai:claude-opus-4-8 · ai:claude-opus-4-8 (range 10-21d) · ai:claude-fable-5

Kept true by its growers

Every fact here carries its source. Grow Cobweb House-leek yourself? What you’ve observed — how it drinks, how it holds its color, a name that’s off — is exactly what keeps this page honest. Contributions are reviewed before anything changes.