Cold hardiness & minimum temperature

Is Opposite-leaf Cliff Stonecrop (Prometheum oppositifolium)cold hardy? Hardiness zone & min temp

Also called Opposite-leaf Cliff Stonecrop, Opposite-leafed Prometheum.

More about opposite-leaf cliff stonecrop

About Opposite-leaf Cliff Stonecrop

Prometheum oppositifolium · also called Opposite-leaf Cliff Stonecrop, Opposite-leafed Prometheum · houseplant

A small, rosette-forming monocarpic succulent from alpine cliff crevices of Turkey and the Caucasus region, related to Rosularia and placed in the recently re-circumscribed genus Prometheum. It forms tight rosettes of opposite, fleshy leaves and tolerates harsh frost when kept dry. Best grown in a gritty alpine mix with bright light and cool winters.

Cold limit: USDA 6–9 · RHS H5 (-15–30°C)

Watch for — Crown rot in wet winters: The combination of cold and moisture is lethal. In pot culture, move to an unheated but frost-protected dry location in winter or cover with a cloche to keep the rosette dry.

What opposite-leaf cliff stonecrop's hardiness rating actually means

Yes — opposite-leaf 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. Opposite-leaf Cliff Stonecrop is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for opposite-leaf 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 opposite-leaf 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 opposite-leaf 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.

Opposite-leaf Cliff Stonecrop hardiness — frequently asked questions

Is opposite-leaf cliff stonecrop cold hardy?

Yes — opposite-leaf 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. Opposite-leaf 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 opposite-leaf cliff stonecrop can survive?

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

What hardiness zone is opposite-leaf cliff stonecrop?

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

Can opposite-leaf 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 opposite-leaf 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.