Cold hardiness & minimum temperature

Is String of pearls (Curio rowleyanus (formerly Senecio rowleyanus))cold hardy? Hardiness zone & min temp

Also called string of beads, rosary plant.

About String of pearls

Curio rowleyanus (formerly Senecio rowleyanus) · also called string of beads, rosary plant · houseplant

String of pearls is a trailing African succulent grown for its dangling strands of pea-shaped leaves. It demands strong light and very sparse watering. Beautiful, brittle, and toxic to pets.

Senecio (Curio) rowleyanus is a trailing succulent in the daisy family native to dry areas of the eastern Cape of South Africa, where it creeps along the ground beneath shrubs and between rocks that shade it from intense sun.

A fast ground-creeping habit that drapes readily over the pot edge; the leaves are mildly toxic and the sap can irritate sensitive skin, so site it away from children and pets.

Cold limit: USDA 10-12 (indoor-only in most US homes) · RHS H1c (18-24°C)

Sources: hort.extension.wisc.edu, plants.ces.ncsu.edu, en.wikipedia.org

What string of pearls's hardiness rating actually means

String of pearls is not cold hardy. It is a tropical houseplant that dies if it is left out through frost — there is no zone where it overwinters outdoors in a UK or cold-US climate. Its RHS rating of H1c means: Warm-temperate — can summer outdoors but must come in well before the first frost. On the US scale that maps to USDA 10-12 (indoor-only 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 5 °C (and never frost). String of pearls has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for string of pearls as it gets too cold:

Below about about 5 °C, growth stalls and the leaves start to show cold stress — dark, water-soaked, or yellowing patches.
A single light frost blackens the foliage; a hard freeze kills the whole plant, roots included, and it does not recover.
Even a cold, draughty windowsill or an unheated porch in winter can be enough to damage it permanently.

Can string of pearls go outside or overwinter — and where?

It can holiday outdoors in summer once nights are reliably above 5 °C, in shade or dappled light, hardened off gradually.
Bring it back indoors well before the first autumn frost — do not wait for a frost warning, move it when nights drop toward 10-12 °C.
It will never overwinter outside in a temperate climate; the indoors is its winter home, full stop.

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 string of pearls can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c figure above.

String of pearls hardiness — frequently asked questions

Is string of pearls cold hardy?

String of pearls is not cold hardy. It is a tropical houseplant that dies if it is left out through frost — there is no zone where it overwinters outdoors in a UK or cold-US climate. Indoor-only in almost every home. String of pearls can only live outside year-round in genuinely frost-free climates (roughly USDA 10-12 (indoor-only in most US homes)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature string of pearls can survive?

Minimum survivable temperature is roughly about 5 °C (and never frost). String of pearls has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

What hardiness zone is string of pearls?

String of pearls is rated USDA 10-12 (indoor-only in most US homes) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can string of pearls survive winter outside?

It can holiday outdoors in summer once nights are reliably above 5 °C, in shade or dappled light, hardened off gradually. Bring it back indoors well before the first autumn frost — do not wait for a frost warning, move it when nights drop toward 10-12 °C. It will never overwinter outside in a temperate climate; the indoors is its winter home, full stop.

What happens to string of pearls below its minimum temperature?

Below about about 5 °C, growth stalls and the leaves start to show cold stress — dark, water-soaked, or yellowing patches. A single light frost blackens the foliage; a hard freeze kills the whole plant, roots included, and it does not recover. Even a cold, draughty windowsill or an unheated porch in winter can be enough to damage it permanently.