Cold hardiness & minimum temperature

Is String of dolphins (Senecio peregrinus)cold hardy? Hardiness zone & min temp

Also called dolphin plant, flying dolphins.

About String of dolphins

Senecio peregrinus · also called dolphin plant, flying dolphins · houseplant

String of dolphins is a quirky succulent hybrid with leaves shaped like leaping dolphins. A cross between string of pearls and Senecio articulatus. Mildly toxic to pets like its parents and demands bright light to keep its distinctive leaf shape.

Curio x peregrinus (Senecio x peregrinus), not a wild species but an intergeneric hybrid of Curio rowleyanus (string of pearls) and a Curio articulatus relative; the leaves curve into two small points resembling leaping dolphins.

A trailing hybrid with cinnamon-scented flowers; vigorous in baskets but the dolphin shape is most pronounced under bright light and lean feeding. Toxic to cats, dogs and humans (pyrrolizidine alkaloids).

Cold limit: USDA 10-11 (indoor in most US homes) · RHS H1c (18-26°C)

Sources: en.wikipedia.org, plants.ces.ncsu.edu

What string of dolphins's hardiness rating actually means

String of dolphins 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 10-11 (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 5 °C (and never frost). String of dolphins has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for string of dolphins 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 dolphins 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 dolphins 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 dolphins hardiness — frequently asked questions

Is string of dolphins cold hardy?

String of dolphins 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 dolphins can only live outside year-round in genuinely frost-free climates (roughly USDA 10-11 (indoor in most US homes)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature string of dolphins can survive?

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

What hardiness zone is string of dolphins?

String of dolphins is rated USDA 10-11 (indoor in most US homes) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can string of dolphins 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 dolphins 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.