Cold hardiness & minimum temperature

Is Old Father Live Forever (Pelargonium cotyledonis)cold hardy? Hardiness zone & min temp

Also called Old Father Live Forever, St Helena Geranium.

More about old father live forever

About Old Father Live Forever

Pelargonium cotyledonis · also called Old Father Live Forever, St Helena Geranium · flowering

Pelargonium cotyledonis is a remarkable succulent-stemmed species endemic to the island of St Helena in the South Atlantic, making it one of the few pelargoniums native outside continental Africa. It forms a thick, pale, water-storing stem topped with large, rounded, slightly hairy leaves and produces clusters of small white flowers. Its unique island origin means it tolerates slightly more moisture and cooler summers than Cape species, but still demands excellent drainage and a frost-free minimum. Toxic to cats, dogs, and horses.

Cold limit: USDA 10-11 (indoor in most climates) · RHS H2 (8–25°C)

Watch for — Stem base rot: The thickened stem is highly susceptible to rot if the compost stays wet, particularly in cool winter conditions. Always water sparingly and ensure very free drainage.

What old father live forever's hardiness rating actually means

Old Father Live Forever 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 10-11 (indoor in most climates) — 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. Old Father Live Forever shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for old father live forever 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 old father live forever go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 10-11 (indoor in most climates) 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 old father live forever 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 old father live forever

Old Father Live Forever 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.

Old Father Live Forever hardiness — frequently asked questions

Is old father live forever cold hardy?

Old Father Live Forever 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 10-11 (indoor in most climates) (and sheltered UK gardens) old father live forever can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature old father live forever can survive?

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

What hardiness zone is old father live forever?

Old Father Live Forever is rated USDA 10-11 (indoor in most climates) and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can old father live forever survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 10-11 (indoor in most climates) 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 old father live forever 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.