A natural spider web
White hairs from leaf tips join above the rosette, protecting the centre like a fine net.
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A tiny alpine rosette with serious winter courage ❄️
Family: Crassulaceae · Pot diameter: 8.5 cm
Sempervivum arachn. 'rubrum' is a small alpine succulent with enormous decorative energy: compact rosettes shift through deep green, burgundy and vivid red, while fine white fibres stretch between leaf tips like a natural spider web. As offsets fill the pot, they create a living mosaic of red circles unlike any typical indoor succulent.
Its real value lies in the combination of appearance and resilience: it is built for outdoor life, tolerates deep winter cold when drainage is correct and changes colour with the season. In summer, mature rosettes may raise pink starry flowers before completing their cycle, leaving younger offsets to continue. It is ideal for a balcony, rock garden or as a gift for someone who forgets that not every succulent belongs indoors.
Three details that turn its botanical identity into genuine presence for a collection and interior or outdoor setting.
White hairs from leaf tips join above the rosette, protecting the centre like a fine net.
Burgundy and red intensify or soften with light, temperature and growth stage.
Each mother rosette produces smaller daughters that gradually fill available mineral ground.
Why you will love it: A succulent offering red colour, natural pattern and real outdoor resilience rather than delicate decoration.
Grow it outdoors on a sunny balcony, in a rock garden, shallow terracotta or a trough with exceptional drainage. A low position lets offsets spread, while protection from prolonged winter rain matters more than protection from cold.
Pair it with plants that genuinely share its light, substrate and seasonal rhythm. Separate pots keep care precise for every plant.
Full sun or a very bright outdoor position, with gradual acclimation after purchase.
Water after the mineral mix dries; avoid persistent winter wet and water held in the crown.
A hardy outdoor plant that needs winter cold, airflow and exceptional drainage.
No spines or latex, but not sold as edible; prevent uncontrolled chewing.
Give it genuine outdoor light. Full sun supports tight rosettes and strong colour, but a greenhouse-grown plant should be acclimated over several days to prevent scorch.
Water thoroughly once the mix dries and allow immediate drainage. Check more often in summer, but winter rain is often the greater risk; prefer a sheltered airy position.
Cobweb fibres hold droplets, so the rosette must dry quickly in open air. Do not grow it in a closed terrarium or indoors year-round.
It follows an outdoor alpine rhythm, tolerating winter cold and renewing rosettes in mild and warm periods. Constant indoor warmth and low light disrupt that cycle.
Use a very mineral, gravelly mix in a shallow pot or rock garden with open drainage. It tolerates cold far better than cold combined with saturated roots.
It needs minimal feeding. With new Sybasoil wait about two months, then use Cactus & Succulent Focus very sparingly only in active growth, never to force size.
The name Sempervivum arachnoideum ‘Rubrum’ is consistently used in horticulture for a red form, but its formal cultivar status is recorded as unresolved. No breeder or date should be invented.
Sempervivum arachnoideum L. is an accepted wild species in Crassulaceae. Cobweb hairs are a species feature, not an artificial trait created by ‘Rubrum’.
The wild species ranges from northern Spain through the Alps and Apennines on temperate mountain rocks.
From natural habitat to care: ‘Rubrum’ is a cultivated colour selection, so ecological context comes from wild Sempervivum arachnoideum in European mountains. Cold is not the main problem there; drainage around the rosette is. Keep it outdoors with sun, air and protection primarily from prolonged winter wet.
Fine hairs extend from leaf tips and join above the centre to create the characteristic web.
A rosette flowers once and then completes its cycle while daughter rosettes continue the cluster.
Stolons and daughter rosettes quickly fill small rocky crevices and replace flowered heads.
Anthocyanins strengthen under high light and lower temperatures, so red colour is not constant year-round.
Useful answers about light, watering, seasonal rhythm and the plant’s correct identity.
Give it genuine outdoor light. Full sun supports tight rosettes and strong colour, but a greenhouse-grown plant should be acclimated over several days to prevent scorch.
Water thoroughly once the mix dries and allow immediate drainage. Check more often in summer, but winter rain is often the greater risk; prefer a sheltered airy position.
Not as a permanent position. It is a hardy outdoor alpine plant needing real sun, air and seasonal cold. Indoors it usually opens, fades and weakens.
It is normal: each rosette is monocarpic. Surrounding offsets remain alive and continue the pot, provided the old head is removed once dry.
Use a very mineral, gravelly mix in a shallow pot or rock garden with open drainage. It tolerates cold far better than cold combined with saturated roots. It needs minimal feeding. With new Sybasoil wait about two months, then use Cactus & Succulent Focus very sparingly only in active growth, never to force size.
No spines or latex, but not sold as edible; prevent uncontrolled chewing.