Cold hardiness & minimum temperature

Is Swiss Rock Jasmine (Androsace helvetica)cold hardy? Hardiness zone & min temp

Also called Swiss Rock Jasmine, Helvetian Androsace.

More about swiss rock jasmine

About Swiss Rock Jasmine

Androsace helvetica · also called Swiss Rock Jasmine, Helvetian Androsace · flowering

Swiss Rock Jasmine is a demanding, very tightly cushioned alpine from the high Alps and Swiss limestone ranges, forming rigid domed mounds of minute hairy rosettes. Tiny white or pale pink flowers with a yellow eye appear almost stemlessly in late spring. Among the most challenging Androsace species, it is prized by specialist alpine growers for its exquisite cushion architecture.

Cold limit: USDA 3–5 · RHS H7 (-25°C to 15°C)

Watch for — Cushion collapse from moisture: Any persistent moisture in the cushion causes irreversible botrytis rot, rapidly turning sections brown and dead. Alpine house cultivation with very low winter watering and maximum ventilation is the primary preventative measure.

What swiss rock jasmine's hardiness rating actually means

Yes — swiss rock jasmine is genuinely cold hardy. Rated RHS H7 and USDA 3–5, 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 3–5 — 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. Swiss Rock Jasmine is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for swiss rock jasmine 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 swiss rock jasmine go outside or overwinter — and where?

Plant it out within USDA 3–5 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 swiss rock jasmine can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Swiss Rock Jasmine hardiness — frequently asked questions

Is swiss rock jasmine cold hardy?

Yes — swiss rock jasmine is genuinely cold hardy. Rated RHS H7 and USDA 3–5, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Swiss Rock Jasmine is hardy across USDA 3–5; 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 swiss rock jasmine can survive?

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

What hardiness zone is swiss rock jasmine?

Swiss Rock Jasmine is rated USDA 3–5 and RHS H7 — Hardy in the severest European continental winters.

Can swiss rock jasmine survive winter outside?

Plant it out within USDA 3–5 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 swiss rock jasmine 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.