Cold hardiness & minimum temperature

Is Sahuc's Sun Rose Hybrid (× Halimiocistus sahucii)cold hardy? Hardiness zone & min temp

Also called Sahuc's sun rose hybrid, Sahuc rock rose.

More about sahuc's sun rose hybrid

About Sahuc's Sun Rose Hybrid

× Halimiocistus sahucii · also called Sahuc's sun rose hybrid, Sahuc rock rose · flowering

× Halimiocistus sahucii is a compact, mound-forming evergreen shrub, a naturally occurring bigeneric hybrid between Halimium umbellatum and Cistus salviifolius, native to southern France. It thrives in full sun with sharply drained, poor to moderately fertile sandy soil, and is highly drought tolerant once established. The most important care rule is to avoid heavy, wet, or fertile soil, which dramatically reduces hardiness and longevity. It is not known to be toxic to pets.

Cold limit: USDA 7-10 · RHS H4 (-10°C to 35°C)

Watch for — Root rot in wet or heavy soils: The primary killer of this plant; poor drainage in winter leads to rapid crown and root rot. Plant on a slope or raised bed with grit incorporated into the planting hole.

What sahuc's sun rose hybrid's hardiness rating actually means

Yes — sahuc's sun rose hybrid is genuinely cold hardy. Rated RHS H4 and USDA 7-10, 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 7-10 — 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. Sahuc's Sun Rose Hybrid is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for sahuc's sun rose hybrid 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 sahuc's sun rose hybrid go outside or overwinter — and where?

Plant it out within USDA 7-10 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 sahuc's sun rose hybrid can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H4 figure above.

Frost protection for borderline sahuc's sun rose hybrid

Sahuc's Sun Rose Hybrid is right on a hardiness edge in many gardens, so if you are pushing it, these measures buy it the margin it needs:

At the cold edge of its range, mulch the root zone in late autumn to buffer the deepest freezes.
Protect container specimens — pots freeze through far faster than open ground, costing roughly a zone of hardiness.
Shelter new growth from late spring frosts with fleece if a hard night is forecast.

Sahuc's Sun Rose Hybrid hardiness — frequently asked questions

Is sahuc's sun rose hybrid cold hardy?

Yes — sahuc's sun rose hybrid is genuinely cold hardy. Rated RHS H4 and USDA 7-10, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Sahuc's Sun Rose Hybrid is hardy across USDA 7-10; 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 sahuc's sun rose hybrid can survive?

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

What hardiness zone is sahuc's sun rose hybrid?

Sahuc's Sun Rose Hybrid is rated USDA 7-10 and RHS H4 — Hardy in an average winter across much of the temperate world.

Can sahuc's sun rose hybrid survive winter outside?

Plant it out within USDA 7-10 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.

How do I protect sahuc's sun rose hybrid from frost?

At the cold edge of its range, mulch the root zone in late autumn to buffer the deepest freezes. Protect container specimens — pots freeze through far faster than open ground, costing roughly a zone of hardiness. Shelter new growth from late spring frosts with fleece if a hard night is forecast.