Cold hardiness & minimum temperature

Is Fringed Houseleek (Sempervivum ciliosum)cold hardy? Hardiness zone & min temp

Also called Fringed Houseleek, Ciliated Houseleek, Teneriffe Houseleek.

More about fringed houseleek

About Fringed Houseleek

Sempervivum ciliosum · also called Fringed Houseleek, Ciliated Houseleek · flowering

Sempervivum ciliosum is a Bulgarian alpine succulent forming compact mats of small, grey-green rosettes densely covered in fine white hairs that give the foliage a frosted, fringed appearance. Native to rocky limestone slopes in Bulgaria and the Balkans, it thrives in full sun with sharply drained gritty soil and is extremely cold-hardy. The key care rule is never allow water to pool in or around the rosettes, especially in winter. Sempervivum is listed as non-toxic to cats and dogs by the ASPCA.

Cold limit: USDA 4-9 · RHS H7 (-34°C to 35°C)

Watch for — Rosette rot (Botrytis or Pythium): Water trapped between the tightly packed hairy leaves, especially in cold wet weather, causes the centre of rosettes to turn brown and rot. Improve drainage, remove affected rosettes promptly, and allow air to circulate; avoid overhead watering.

What fringed houseleek's hardiness rating actually means

Yes — fringed houseleek is genuinely cold hardy. Rated RHS H7 and USDA 4-9, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H7 means: Hardy in the severest European continental winters. On the US scale that maps to USDA 4-9 — 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 below about −20 °C. Fringed Houseleek is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for fringed houseleek as it gets too cold:

It tolerates winter lows to about −20 °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 fringed houseleek go outside or overwinter — and where?

Plant it out within USDA 4-9 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 fringed houseleek can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Fringed Houseleek hardiness — frequently asked questions

Is fringed houseleek cold hardy?

Yes — fringed houseleek is genuinely cold hardy. Rated RHS H7 and USDA 4-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Fringed Houseleek is hardy across USDA 4-9; 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 fringed houseleek can survive?

Minimum survivable temperature is roughly below about −20 °C. Fringed Houseleek is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is fringed houseleek?

Fringed Houseleek is rated USDA 4-9 and RHS H7 — Hardy in the severest European continental winters.

Can fringed houseleek survive winter outside?

Plant it out within USDA 4-9 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 fringed houseleek below its minimum temperature?

It tolerates winter lows to about −20 °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.