Cold hardiness & minimum temperature

Is Rough-leaved Cape Mallow (Anisodontea scabrosa)cold hardy? Hardiness zone & min temp

Also called Rough-leaved Cape Mallow, Rough-leaf African Mallow, Hairy Mallow, Pink Mallow.

More about rough-leaved cape mallow

About Rough-leaved Cape Mallow

Anisodontea scabrosa · also called Rough-leaved Cape Mallow, Rough-leaf African Mallow · flowering

Anisodontea scabrosa is a vigorous, evergreen shrub from the Cape Floristic Region of South Africa, named for its distinctly rough, hairy leaves, and valued for its prolific, small, deep-pink to magenta hibiscus-like flowers produced from spring until the first frost or year-round in warm climates. It is larger and somewhat hardier than its close relative A. capensis, tolerating brief light frosts in a sheltered position, but performing best in USDA zones 8–11 with well-drained soil and full sun. Prune hard in early spring to prevent it becoming woody and bare at the base. No toxic principles are documented for the genus, though it is not formally listed as non-toxic by the ASPCA.

Cold limit: USDA 8-11 · RHS H3 (-3 to 32°C)

What rough-leaved cape mallow's hardiness rating actually means

Rough-leaved Cape Mallow 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 8-11 — 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. Rough-leaved Cape Mallow shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for rough-leaved cape mallow 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 rough-leaved cape mallow go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 8-11 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 rough-leaved cape mallow 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 rough-leaved cape mallow

Rough-leaved Cape Mallow 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.

Rough-leaved Cape Mallow hardiness — frequently asked questions

Is rough-leaved cape mallow cold hardy?

Rough-leaved Cape Mallow 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 8-11 (and sheltered UK gardens) rough-leaved cape mallow can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature rough-leaved cape mallow can survive?

Minimum survivable temperature is roughly about −5 to 1 °C — a light, short frost only. Rough-leaved Cape Mallow shrugs off cold nights but a real, sustained freeze will kill it.

What hardiness zone is rough-leaved cape mallow?

Rough-leaved Cape Mallow is rated USDA 8-11 and RHS H3 — Half-hardy — comes through mild UK winters outside but is killed by a hard freeze.

Can rough-leaved cape mallow survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 8-11 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 rough-leaved cape mallow 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.