Cold hardiness & minimum temperature

Is Rose Geranium (Pelargonium graveolens)cold hardy? Hardiness zone & min temp

Also called Rose Geranium, Rose-scented Pelargonium, Sweet-scented Geranium.

More about rose geranium

About Rose Geranium

Pelargonium graveolens · also called Rose Geranium, Rose-scented Pelargonium · herb

Pelargonium graveolens is a vigorous, shrubby scented-leaf pelargonium from the Cape region of South Africa, grown principally for its intensely rose-lemon fragrant, deeply lobed leaves, which are used in perfumery, aromatherapy, and cooking. It produces small pale pink flowers with darker markings but the foliage is the main attraction. It wants full sun, free-draining compost, and a frost-free winter rest; in the UK and cool US climates it performs best as a patio container plant brought indoors before the first frost. Toxic to cats and dogs.

Cold limit: USDA 9-11 (overwinter frost-free in colder zones) · RHS H2 (10-28°C)

Watch for — Black leg: Rotting and blackening of the stem base, usually from overwatering or cold, wet compost. Use very gritty compost, allow it to dry between waterings, and discard severely affected plants to prevent spread.

What rose geranium's hardiness rating actually means

Rose Geranium is half-hardy (RHS H2). 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 H2 means: Tender — survives a frost-free greenhouse or a very mild, sheltered spot. On the US scale that maps to USDA 9-11 (overwinter frost-free in colder zones) — 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 1 to 5 °C — tolerates cold but no real frost. Rose Geranium shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for rose geranium as it gets too cold:

Down to roughly about 1 to 5 °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 rose geranium go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-11 (overwinter frost-free in colder zones) 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 rose geranium can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H2 figure above.

Frost protection for borderline rose geranium

Rose Geranium 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.

Rose Geranium hardiness — frequently asked questions

Is rose geranium cold hardy?

Rose Geranium is half-hardy (RHS H2). 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 (overwinter frost-free in colder zones) (and sheltered UK gardens) rose geranium can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature rose geranium can survive?

Minimum survivable temperature is roughly about 1 to 5 °C — tolerates cold but no real frost. Rose Geranium shrugs off cold nights but a real, sustained freeze will kill it.

What hardiness zone is rose geranium?

Rose Geranium is rated USDA 9-11 (overwinter frost-free in colder zones) and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can rose geranium survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-11 (overwinter frost-free in colder zones) 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 rose geranium 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.