Cold hardiness & minimum temperature

Is String of needles (Ceropegia linearis)cold hardy? Hardiness zone & min temp

Also called string of needles, needle vine, Ceropegia linearis.

More about string of needles

About String of needles

Ceropegia linearis · also called string of needles, needle vine · houseplant

String of needles is a trailing South African succulent, a close relative of string of hearts, with slender needle-thin green leaves on wiry stems. It wants bright indirect light and sparse watering, and roots easily from cuttings. Treat as mildly toxic to pets and keep the strands out of reach.

Cold limit: USDA 11-12 (indoor in most US and UK homes) (10-30°C)

What string of needles's hardiness rating actually means

String of needles 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 H1b means: Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season. On the US scale that maps to USDA 11-12 (indoor in most US and UK 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 10 °C (sustained cold below this is damaging). String of needles has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Below about about 10 °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 needles go outside or overwinter — and where?

It can holiday outdoors in summer once nights are reliably above 10 °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 needles can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1b figure above.

String of needles hardiness — frequently asked questions

Is string of needles cold hardy?

String of needles 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 needles can only live outside year-round in genuinely frost-free climates (roughly USDA 11-12 (indoor in most US and UK homes)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature string of needles can survive?

What hardiness zone is string of needles?

String of needles is rated USDA 11-12 (indoor in most US and UK homes) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can string of needles survive winter outside?

It can holiday outdoors in summer once nights are reliably above 10 °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 needles below its minimum temperature?

Below about about 10 °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.