Cold hardiness & minimum temperature

Is Greater Sea Spurrey (Spergularia media)cold hardy? Hardiness zone & min temp

Also called Greater Sea Spurrey, Greater Sea-spurrey.

More about greater sea spurrey

About Greater Sea Spurrey

Spergularia media · also called Greater Sea Spurrey, Greater Sea-spurrey · flowering

Spergularia media is a perennial or biennial halophyte native to the saltmarshes and rocky coastal margins of Europe, North Africa, and western Asia, occurring throughout the British coastline. It forms low, sprawling mats of fleshy, linear leaves and produces pale pink to white flowers with five petals that open fully in sun from June to September. The key care requirement is saline-tolerant, freely draining sandy or muddy coastal substrate; it will not persist in ordinary garden soil without a degree of salt. This species has no ASPCA toxicity listing; classified as mildly-toxic as a precaution.

Cold limit: USDA 5-9 · RHS H5 (-5–25°C)

What greater sea spurrey's hardiness rating actually means

Yes — greater sea spurrey is genuinely cold hardy. Rated RHS H5 and USDA 5-9, 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 5-9 — 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. Greater Sea Spurrey is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for greater sea spurrey 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 greater sea spurrey go outside or overwinter — and where?

Plant it out within USDA 5-9 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 greater sea spurrey can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Greater Sea Spurrey hardiness — frequently asked questions

Is greater sea spurrey cold hardy?

Yes — greater sea spurrey is genuinely cold hardy. Rated RHS H5 and USDA 5-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Greater Sea Spurrey is hardy across USDA 5-9; 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 greater sea spurrey can survive?

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

What hardiness zone is greater sea spurrey?

Greater Sea Spurrey is rated USDA 5-9 and RHS H5 — Hardy in most of the UK and in cold winters.

Can greater sea spurrey survive winter outside?

Plant it out within USDA 5-9 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 greater sea spurrey 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.