Cold hardiness & minimum temperature

Is Caralluma europaea (Caralluma europaea)cold hardy? Hardiness zone & min temp

Also called European caralluma, famine food plant.

More about caralluma europaea

About Caralluma europaea

Caralluma europaea · also called European caralluma, famine food plant · houseplant

Caralluma europaea is a low, clump-forming stapeliad succulent from North Africa and southern Spain, grown for its four-angled grey-green stems and star-shaped, dark-veined carrion flowers. It is a tough, drought-hardy windowsill plant that wants gritty soil, bright sun, and near-bone-dry winters. Like all stapeliads it rots fast if overwatered.

Cold limit: USDA 9b-11 (indoor in most US homes) · RHS H2 (18-30C)

Watch for — Winter cold-wet damage: Watering during cool dormancy causes translucent, mushy stem bases. Keep nearly dry and above 12C from autumn to early spring.

What caralluma europaea's hardiness rating actually means

Caralluma europaea 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 9b-11 (indoor in most US homes) — 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. Caralluma europaea shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for caralluma europaea 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 caralluma europaea go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 9b-11 (indoor in most US homes) 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 caralluma europaea 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 caralluma europaea

Caralluma europaea 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.

Caralluma europaea hardiness — frequently asked questions

Is caralluma europaea cold hardy?

Caralluma europaea 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 9b-11 (indoor in most US homes) (and sheltered UK gardens) caralluma europaea can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature caralluma europaea can survive?

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

What hardiness zone is caralluma europaea?

Caralluma europaea is rated USDA 9b-11 (indoor in most US homes) and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can caralluma europaea survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 9b-11 (indoor in most US homes) 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 caralluma europaea 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.