Cold hardiness & minimum temperature

Is Cobweb Houseleek (Sempervivum arachnoideum)cold hardy? Hardiness zone & min temp

Also called Cobweb Hens and Chicks.

More about cobweb houseleek

About Cobweb Houseleek

Sempervivum arachnoideum · also called Cobweb Hens and Chicks · houseplant

Cobweb Houseleek forms tight rosettes of green-to-red leaves laced with fine white cobweb-like hairs across the tips, a distinctive alpine trait. It clusters into mats of offset 'chicks', tolerates frost and drought, and dies after flowering while leaving offsets behind. Hardy, low-care, and ASPCA non-toxic to cats and dogs.

Cold limit: USDA 5-8 (hardy alpine; grows outdoors year-round) · RHS H5 (-20 to 28°C)

What cobweb houseleek's hardiness rating actually means

Yes — cobweb houseleek is genuinely cold hardy. Rated RHS H5 and USDA 5-8 (hardy alpine; grows outdoors year-round), it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H5 means: Hardy in most of the UK and in cold winters. On the US scale that maps to USDA 5-8 (hardy alpine; grows outdoors year-round) — the zones where it can be left outdoors year-round.

New to these scales? The USDA hardiness zone map explained covers how the zone numbers work, and you can find your own zone with the zone finder.

Minimum temperature — and what happens below it

Minimum survivable temperature is roughly about −15 to −10 °C. Cobweb Houseleek is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for cobweb houseleek as it gets too cold:

It tolerates winter lows to about −15 to −10 °C once established.
Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root.
First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.

Can cobweb houseleek go outside or overwinter — and where?

Plant it out within USDA 5-8 (hardy alpine; grows outdoors year-round) and it overwinters with little or no help.
It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy.
The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

Work back from your local frost dates with the frost-date calculator: the last spring frost and first autumn frost are what really decide when cobweb houseleek can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Cobweb Houseleek hardiness — frequently asked questions

Is cobweb houseleek cold hardy?

Yes — cobweb houseleek is genuinely cold hardy. Rated RHS H5 and USDA 5-8 (hardy alpine; grows outdoors year-round), it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Cobweb Houseleek is hardy across USDA 5-8 (hardy alpine; grows outdoors year-round); it belongs in the ground or a frost-proof container, not on a windowsill, and many types actively need a cold winter to perform.

What is the minimum temperature cobweb houseleek can survive?

Minimum survivable temperature is roughly about −15 to −10 °C. Cobweb Houseleek is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is cobweb houseleek?

Cobweb Houseleek is rated USDA 5-8 (hardy alpine; grows outdoors year-round) and RHS H5 — Hardy in most of the UK and in cold winters.

Can cobweb houseleek survive winter outside?

Plant it out within USDA 5-8 (hardy alpine; grows outdoors year-round) and it overwinters with little or no help. It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy. The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

What happens to cobweb houseleek below its minimum temperature?

It tolerates winter lows to about −15 to −10 °C once established. Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root. First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.