Cold hardiness & minimum temperature

Is Houseleek Rosularia (Rosularia sempervivum)cold hardy? Hardiness zone & min temp

Also called Houseleek Rosularia, Sempervivum Rosularia.

More about houseleek rosularia

About Houseleek Rosularia

Rosularia sempervivum · also called Houseleek Rosularia, Sempervivum Rosularia · houseplant

Rosularia sempervivum is a compact alpine succulent from the Caucasus and Turkey, forming low mats of fleshy rosettes resembling miniature houseleeks. Creamy-yellow flowers appear in summer on slender stems. It thrives in bright, sunny spots with gritty soil and minimal water, making it ideal for rock gardens, alpine troughs, and sunny windowsills.

Cold limit: USDA 5–9 · RHS H5 (-10–28°C)

What houseleek rosularia's hardiness rating actually means

Yes — houseleek rosularia is genuinely cold hardy. Rated RHS H5 and USDA 5–9, 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 5–9 — 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 about −15 to −10 °C. Houseleek Rosularia is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for houseleek rosularia 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 houseleek rosularia go outside or overwinter — and where?

Plant it out within USDA 5–9 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 houseleek rosularia can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Houseleek Rosularia hardiness — frequently asked questions

Is houseleek rosularia cold hardy?

Yes — houseleek rosularia is genuinely cold hardy. Rated RHS H5 and USDA 5–9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Houseleek Rosularia is hardy across USDA 5–9; 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 houseleek rosularia can survive?

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

What hardiness zone is houseleek rosularia?

Houseleek Rosularia is rated USDA 5–9 and RHS H5 — Hardy in most of the UK and in cold winters.

Can houseleek rosularia survive winter outside?

Plant it out within USDA 5–9 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 houseleek rosularia 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.