Cold hardiness & minimum temperature

Is Hairy Sun Rose (Halimium lasianthum)cold hardy? Hardiness zone & min temp

Also called Hairy Sun Rose, Spotted Sun Rose.

More about hairy sun rose

About Hairy Sun Rose

Halimium lasianthum · also called Hairy Sun Rose, Spotted Sun Rose · flowering

Halimium lasianthum is an evergreen, mound-forming shrub in the Cistaceae family, native to rocky, sandy soils in Spain and Portugal. It bears a generous display of bright yellow flowers, each typically marked with a dark chocolate-crimson basal spot, in late spring and early summer. Like all Halimium, it demands full sun and excellent drainage and is highly resistant to summer drought once established, making it excellent for Mediterranean-style borders, gravel gardens, and coastal plantings. No ASPCA toxicity data is available for this species; it is classified as mildly-toxic as a precaution.

Cold limit: USDA 8-10 · RHS H4 (-8 to 38 °C)

Watch for — Root and stem rot in wet or heavy soils: Persistently moist or waterlogged soils quickly lead to Phytophthora root rot and collapse of the plant, especially in winter. Plant in raised or sharply drained beds and avoid any mulch that holds moisture against the crown.

What hairy sun rose's hardiness rating actually means

Yes — hairy 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. Hairy Sun Rose is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for hairy 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 hairy 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 hairy 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.

Hairy Sun Rose hardiness — frequently asked questions

Is hairy sun rose cold hardy?

Yes — hairy 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. Hairy 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 hairy sun rose can survive?

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

What hardiness zone is hairy sun rose?

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

Can hairy 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 hairy 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.