Cold hardiness & minimum temperature

Is Pelargonium capitatum (Pelargonium capitatum)cold hardy? Hardiness zone & min temp

Also called Rose pelargonium, Wild rose geranium, Rose-scented geranium.

More about pelargonium capitatum

About Pelargonium capitatum

Pelargonium capitatum · also called Rose pelargonium, Wild rose geranium · herb

Pelargonium capitatum is a sprawling, soft-stemmed South African species with lobed, crinkled, rose-scented leaves and rounded heads of small pink-mauve flowers. A coastal plant naturalised on dunes in its range, it is a parent of the rose-geranium oil trade and grown for fragrant foliage. Vigorous and drought-tolerant, it wants full sun and very sharp drainage.

Cold limit: USDA 9-11 (frost-tender; overwinter under cover where frost occurs) · RHS H2 (10-24°C)

Watch for — Soft-stem and root rot: Its succulent sprawling stems rot fast in wet soil. Use very sharp drainage, water only when well dry and avoid waterlogging, especially in winter.

What pelargonium capitatum's hardiness rating actually means

Pelargonium capitatum 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 (frost-tender; overwinter under cover where frost occurs) — 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. Pelargonium capitatum shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for pelargonium capitatum 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 pelargonium capitatum go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-11 (frost-tender; overwinter under cover where frost occurs) 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 pelargonium capitatum 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 pelargonium capitatum

Pelargonium capitatum 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.

Pelargonium capitatum hardiness — frequently asked questions

Is pelargonium capitatum cold hardy?

Pelargonium capitatum 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 (frost-tender; overwinter under cover where frost occurs) (and sheltered UK gardens) pelargonium capitatum can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature pelargonium capitatum can survive?

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

What hardiness zone is pelargonium capitatum?

Pelargonium capitatum is rated USDA 9-11 (frost-tender; overwinter under cover where frost occurs) and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can pelargonium capitatum survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-11 (frost-tender; overwinter under cover where frost occurs) 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 pelargonium capitatum 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.