Cold hardiness & minimum temperature

Is Pine-scented Pelargonium (Pelargonium denticulatum)cold hardy? Hardiness zone & min temp

Also called Pine-scented Pelargonium, Fernleaf Pelargonium, Toothed Pelargonium, Pine Geranium.

More about pine-scented pelargonium

About Pine-scented Pelargonium

Pelargonium denticulatum · also called Pine-scented Pelargonium, Fernleaf Pelargonium · herb

Pelargonium denticulatum is a finely cut-leaved, strongly aromatic species from South Africa's Western Cape, grown for its distinctively piny, balsamic-pine fragrance released on the slightest touch of the sticky, deeply toothed foliage. Upright in habit with small, pale to mid-pink flowers, it makes an excellent scented conservatory or patio container plant valued as much for olfactory interest as for ornament. It requires full sun, free-draining compost, and frost-free overwintering in all but the mildest UK and US gardens. Toxic to cats and dogs.

Cold limit: USDA 9-11 (bring under cover before first frost in colder zones) · RHS H2 (8-27°C)

Watch for — Pelargonium rust: Brown pustule rings on leaf undersides; worse in humid summers or indoor overwintering conditions. Strip affected leaves, move to a more ventilated spot, and apply a copper-based fungicide if the outbreak is severe.

What pine-scented pelargonium's hardiness rating actually means

Pine-scented Pelargonium 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 (bring under cover before first frost 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. Pine-scented Pelargonium shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for pine-scented pelargonium 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 pine-scented pelargonium go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-11 (bring under cover before first frost 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 pine-scented pelargonium 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 pine-scented pelargonium

Pine-scented Pelargonium 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.

Pine-scented Pelargonium hardiness — frequently asked questions

Is pine-scented pelargonium cold hardy?

Pine-scented Pelargonium 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 (bring under cover before first frost in colder zones) (and sheltered UK gardens) pine-scented pelargonium can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature pine-scented pelargonium can survive?

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

What hardiness zone is pine-scented pelargonium?

Pine-scented Pelargonium is rated USDA 9-11 (bring under cover before first frost in colder zones) and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can pine-scented pelargonium survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-11 (bring under cover before first frost 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 pine-scented pelargonium 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.