Cold hardiness & minimum temperature

Is White Campion (Silene latifolia)cold hardy? Hardiness zone & min temp

Also called White Campion, White Cockle, Evening Lychnis.

More about white campion

About White Campion

Silene latifolia · also called White Campion, White Cockle · flowering

Silene latifolia is a dioecious biennial or short-lived perennial native to disturbed ground, roadsides, and arable margins across Europe and introduced across North America. Its white, five-petalled flowers open in the evening and are fragrant, attracting moths and other nocturnal pollinators. The most critical care note is that it resents waterlogging, especially in winter, and needs sharp drainage to persist. As with other Silene species it contains saponins and is treated as mildly toxic to pets in the absence of ASPCA listing.

Cold limit: USDA 3-8 · RHS H6 (-20 to 25°C)

What white campion's hardiness rating actually means

Yes — white campion is genuinely cold hardy. Rated RHS H6 and USDA 3-8, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H6 means: Hardy throughout the UK and northern Europe. On the US scale that maps to USDA 3-8 — 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 −20 to −15 °C. White Campion is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for white campion as it gets too cold:

It tolerates winter lows to about −20 to −15 °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 white campion go outside or overwinter — and where?

Plant it out within USDA 3-8 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 white campion can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

White Campion hardiness — frequently asked questions

Is white campion cold hardy?

Yes — white campion is genuinely cold hardy. Rated RHS H6 and USDA 3-8, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. White Campion is hardy across USDA 3-8; 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 white campion can survive?

Minimum survivable temperature is roughly about −20 to −15 °C. White Campion is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is white campion?

White Campion is rated USDA 3-8 and RHS H6 — Hardy throughout the UK and northern Europe.

Can white campion survive winter outside?

Plant it out within USDA 3-8 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 white campion below its minimum temperature?

It tolerates winter lows to about −20 to −15 °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.