Cold hardiness & minimum temperature

Is Sea Purslane Sun Rose (Halimium halimifolium)cold hardy? Hardiness zone & min temp

Also called Sea Purslane Sun Rose, Grey-Leaved Sun Rose, Halimium.

More about sea purslane sun rose

About Sea Purslane Sun Rose

Halimium halimifolium · also called Sea Purslane Sun Rose, Grey-Leaved Sun Rose · flowering

Halimium halimifolium is an evergreen or semi-evergreen shrub in the Cistaceae family, widespread across the western Mediterranean region from Portugal and Spain to northwest Africa and into Italy, typically growing in dry coastal sands and garrigue scrub. Its greyish-white woolly leaves resemble those of sea purslane (Atriplex portulacoides) — hence the name — and it bears masses of bright yellow, sometimes dark-blotched flowers in late spring to early summer. It excels in hot, dry coastal gardens on free-draining soils and is one of the hardier Halimium species. It is conservatively classified as mildly-toxic for pets, as no ASPCA assessment is available.

Cold limit: USDA 8-10 · RHS H4 (-8 to 40 °C)

Watch for — Waterlogging and winter wet: Even brief periods of waterlogging in winter can trigger fatal root rot. In heavier soils or high-rainfall areas, plant into raised beds or mix in up to 50% grit and plant on a slight slope so water cannot pool around the crown.

What sea purslane sun rose's hardiness rating actually means

Yes — sea purslane sun rose is genuinely cold hardy. Rated RHS H4 and USDA 8-10, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H4 means: Hardy in an average winter across much of the temperate world. On the US scale that maps to USDA 8-10 — 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 −10 to −5 °C. Sea Purslane Sun Rose is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for sea purslane sun rose as it gets too cold:

It tolerates winter lows to about −10 to −5 °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 sea purslane sun rose go outside or overwinter — and where?

Plant it out within USDA 8-10 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 sea purslane sun rose can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H4 figure above.

Sea Purslane Sun Rose hardiness — frequently asked questions

Is sea purslane sun rose cold hardy?

Yes — sea purslane sun rose is genuinely cold hardy. Rated RHS H4 and USDA 8-10, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Sea Purslane Sun Rose is hardy across USDA 8-10; 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 sea purslane sun rose can survive?

Minimum survivable temperature is roughly about −10 to −5 °C. Sea Purslane Sun Rose is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is sea purslane sun rose?

Sea Purslane Sun Rose is rated USDA 8-10 and RHS H4 — Hardy in an average winter across much of the temperate world.

Can sea purslane sun rose survive winter outside?

Plant it out within USDA 8-10 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 sea purslane sun rose below its minimum temperature?

It tolerates winter lows to about −10 to −5 °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.