Cold hardiness & minimum temperature

Is Alpine Campion (Silene alpestris)cold hardy? Hardiness zone & min temp

Also called Alpine campion, Alpine catchfly, Alps campion.

More about alpine campion

About Alpine Campion

Silene alpestris · also called Alpine campion, Alpine catchfly · flowering

Silene alpestris is a low, mat-forming evergreen perennial native to rocky, subalpine meadows and scree slopes in the Eastern Alps and Apennines. From late spring into early summer it produces showers of small, deeply fringed, star-shaped white flowers on slender branching stems above compact dark-green foliage. It thrives in moderately fertile, gritty, neutral to alkaline, well-drained soil in full sun or light part-shade, and strongly resents winter wet. The ASPCA lists the related Silene acaulis (moss campion) as non-toxic to dogs, cats, and horses; Silene alpestris is classified as mildly-toxic in the absence of a species-specific ASPCA listing.

Cold limit: USDA 4-7 · RHS H7 (-25°C to 25°C)

Watch for — Crown rot in winter wet: Plants grown in poorly drained soil often die over winter; mulching the crown with grit and ensuring the site never lies wet is the best prevention.

What alpine campion's hardiness rating actually means

Yes — alpine campion is genuinely cold hardy. Rated RHS H7 and USDA 4-7, 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 4-7 — 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. Alpine Campion is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for alpine campion 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 alpine campion go outside or overwinter — and where?

Plant it out within USDA 4-7 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 alpine campion can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Alpine Campion hardiness — frequently asked questions

Is alpine campion cold hardy?

Yes — alpine campion is genuinely cold hardy. Rated RHS H7 and USDA 4-7, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Alpine Campion is hardy across USDA 4-7; 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 alpine campion can survive?

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

What hardiness zone is alpine campion?

Alpine Campion is rated USDA 4-7 and RHS H7 — Hardy in the severest European continental winters.

Can alpine campion survive winter outside?

Plant it out within USDA 4-7 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 alpine campion 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.