Cold hardiness & minimum temperature

Is Poplar-Leaved Rock Rose (Cistus populifolius)cold hardy? Hardiness zone & min temp

Also called Poplar-leaved rock rose, Large-leaved rock rose.

More about poplar-leaved rock rose

About Poplar-Leaved Rock Rose

Cistus populifolius · also called Poplar-leaved rock rose, Large-leaved rock rose · flowering

Cistus populifolius is a vigorous, large-leaved evergreen shrub native to the Iberian Peninsula and south-west France, recognised by its broadly ovate, poplar-like leaves with heart-shaped bases — distinctively large for a Cistus. In June it bears white, 5-petalled flowers up to 5 cm (2 in) across, each with a yellow basal stain, in clusters from the previous year's wood. It is one of the hardier rock roses, tolerating moderate frost when sited in a well-drained, sunny spot, and once established it is highly drought-tolerant. Cistus is not listed by the ASPCA as explicitly non-toxic; treat as mildly toxic as a precaution.

Cold limit: USDA 7-10 · RHS H4 (-8 to 35°C)

Watch for — Waterlogging in winter: Despite being one of the hardier Cistus species, prolonged wet soils in winter encourage phytophthora root rot; ensure free-draining soil or plant on a slope and avoid low-lying frost pockets where cold air and wet pool together.

What poplar-leaved rock rose's hardiness rating actually means

Yes — poplar-leaved rock rose 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. Poplar-Leaved Rock Rose is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for poplar-leaved rock 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 poplar-leaved rock rose 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 poplar-leaved rock rose 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 poplar-leaved rock rose

Poplar-Leaved Rock Rose 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.

Poplar-Leaved Rock Rose hardiness — frequently asked questions

Is poplar-leaved rock rose cold hardy?

Yes — poplar-leaved rock rose 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. Poplar-Leaved Rock Rose 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 poplar-leaved rock rose can survive?

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

What hardiness zone is poplar-leaved rock rose?

Poplar-Leaved Rock Rose is rated USDA 7-10 and RHS H4 — Hardy in an average winter across much of the temperate world.

Can poplar-leaved rock rose 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 poplar-leaved rock rose 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.