Cold hardiness & minimum temperature

Is Munby's Rock Rose (Cistus munbyi)cold hardy? Hardiness zone & min temp

Also called Munby's rock rose.

More about munby's rock rose

About Munby's Rock Rose

Cistus munbyi · also called Munby's rock rose · flowering

Cistus munbyi is a small, evergreen shrub native to the low-elevation Mediterranean coasts of Morocco and Algeria, where it grows in dry, sunny, alkaline scrubland at up to 100 m altitude. It produces white flowers above narrow, linear leaves with revolute (downward-rolled) margins, and is strongly adapted to hot, dry, well-drained conditions. Because it hails from a mild coastal climate it has limited frost tolerance and should be given a sheltered, sunny position or brought under cover in cold winters. Cistus is not listed by the ASPCA as explicitly non-toxic; treat as mildly toxic as a precaution.

Cold limit: USDA 9-11 · RHS H3 (0 to 38°C)

Watch for — Frost damage and dieback: More frost-tender than many rock roses due to its North African coastal origin; temperatures below 0°C (32°F) can damage stems. Protect with horticultural fleece or grow in a pot that can be moved under cover in winter.

What munby's rock rose's hardiness rating actually means

Munby's Rock Rose is half-hardy (RHS H3). It survives a mild winter outdoors in a sheltered spot, but a hard frost kills it — so in colder zones it is lifted, potted, or grown as a tender plant. Its RHS rating of H3 means: Half-hardy — comes through mild UK winters outside but is killed by a hard freeze. On the US scale that maps to USDA 9-11 — 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 −5 to 1 °C — a light, short frost only. Munby's Rock Rose shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for munby's rock rose as it gets too cold:

Down to roughly about −5 to 1 °C it copes, especially if dry and sheltered.
A sustained hard frost collapses the top growth; whether it returns depends on whether the roots, crown or tubers froze.
Wet cold is far more lethal than dry cold for this plant — soggy, frozen soil is the usual killer.

Can munby's rock rose go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-11 or a frost-free UK microclimate.
In colder zones, grow it in a pot you can move under cover, or lift its tubers/roots and store them frost-free over winter.
A south-facing wall, free-draining soil and a dry winter position can push it a full zone hardier than the books suggest.

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 munby's rock rose can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H3 figure above.

Frost protection for borderline munby's rock rose

Munby's 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:

Mulch the crown or root zone deeply with bark, straw or leaf-mould before the first hard frost.
Move container plants against a warm wall or into an unheated but frost-free porch or greenhouse.
Fleece the top growth on the coldest nights, and keep it on the dry side — dry roots survive cold far better than wet ones.
Lift dahlia-type tubers or tender crowns after the first light frost blackens the foliage and store them somewhere cool but frost-free.

Munby's Rock Rose hardiness — frequently asked questions

Is munby's rock rose cold hardy?

Munby's Rock Rose is half-hardy (RHS H3). It survives a mild winter outdoors in a sheltered spot, but a hard frost kills it — so in colder zones it is lifted, potted, or grown as a tender plant. Borderline outdoors. In its mild end of USDA 9-11 (and sheltered UK gardens) munby's rock rose can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature munby's rock rose can survive?

Minimum survivable temperature is roughly about −5 to 1 °C — a light, short frost only. Munby's Rock Rose shrugs off cold nights but a real, sustained freeze will kill it.

What hardiness zone is munby's rock rose?

Munby's Rock Rose is rated USDA 9-11 and RHS H3 — Half-hardy — comes through mild UK winters outside but is killed by a hard freeze.

Can munby's rock rose survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-11 or a frost-free UK microclimate. In colder zones, grow it in a pot you can move under cover, or lift its tubers/roots and store them frost-free over winter. A south-facing wall, free-draining soil and a dry winter position can push it a full zone hardier than the books suggest.

How do I protect munby's rock rose from frost?

Mulch the crown or root zone deeply with bark, straw or leaf-mould before the first hard frost. Move container plants against a warm wall or into an unheated but frost-free porch or greenhouse. Fleece the top growth on the coldest nights, and keep it on the dry side — dry roots survive cold far better than wet ones. Lift dahlia-type tubers or tender crowns after the first light frost blackens the foliage and store them somewhere cool but frost-free.