Cold hardiness & minimum temperature

Is Fringed Cliff Stonecrop (Prometheum fimbriatum)cold hardy? Hardiness zone & min temp

Also called Fringed Cliff Stonecrop.

More about fringed cliff stonecrop

About Fringed Cliff Stonecrop

Prometheum fimbriatum · also called Fringed Cliff Stonecrop · houseplant

A rare mat-forming alpine succulent from rocky cliff habitats in Turkey and the wider southwestern Asian mountain range. Like other Prometheum species, it forms compact rosettes of fleshy fringed leaves that spread via offsets to create a cushion. The finely ciliate (fringed) leaf margins distinguish it from related species. Very cold hardy; suited to rock gardens, troughs, and alpine house collections.

Cold limit: USDA 6–9 · RHS H5 (-20 to 25°C)

What fringed cliff stonecrop's hardiness rating actually means

Yes — fringed cliff stonecrop is genuinely cold hardy. Rated RHS H5 and USDA 6–9, 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 6–9 — 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. Fringed Cliff Stonecrop is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for fringed cliff stonecrop 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 fringed cliff stonecrop go outside or overwinter — and where?

Plant it out within USDA 6–9 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 cliff stonecrop can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Fringed Cliff Stonecrop hardiness — frequently asked questions

Is fringed cliff stonecrop cold hardy?

Yes — fringed cliff stonecrop is genuinely cold hardy. Rated RHS H5 and USDA 6–9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Fringed Cliff Stonecrop is hardy across USDA 6–9; 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 cliff stonecrop can survive?

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

What hardiness zone is fringed cliff stonecrop?

Fringed Cliff Stonecrop is rated USDA 6–9 and RHS H5 — Hardy in most of the UK and in cold winters.

Can fringed cliff stonecrop survive winter outside?

Plant it out within USDA 6–9 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 cliff stonecrop 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.