Cold hardiness & minimum temperature

Is Candle plant (Senecio articulatus (syn. Curio articulatus))cold hardy? Hardiness zone & min temp

Also called hot dog cactus, candlestick plant, sausage plant.

More about candle plant

About Candle plant

Senecio articulatus (syn. Curio articulatus) · also called hot dog cactus, candlestick plant · houseplant

Candle plant is a South African succulent grown for its jointed, sausage-like blue-grey stems. It is a winter grower that wants strong light and very sparse watering, going dormant in summer heat. Keep it well out of reach: its genus, Senecio, is flagged toxic to pets by the ASPCA.

Cold limit: USDA 9b-11 (indoor-only in most US and UK homes; RHS H1c) (10-25°C)

Watch for — Drops leaves and looks dormant in summer: Normal. This is a winter grower that rests in summer heat; ease off watering and wait.

What candle plant's hardiness rating actually means

Candle plant 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 9b-11 (indoor-only in most US and UK homes; RHS H1c) — 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). Candle plant has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for candle plant 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 candle plant 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 candle plant can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1b figure above.

Candle plant hardiness — frequently asked questions

Is candle plant cold hardy?

Candle plant 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. Candle plant can only live outside year-round in genuinely frost-free climates (roughly USDA 9b-11 (indoor-only in most US and UK homes; RHS H1c)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature candle plant can survive?

Minimum survivable temperature is roughly about 10 °C (sustained cold below this is damaging). Candle plant has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

What hardiness zone is candle plant?

Candle plant is rated USDA 9b-11 (indoor-only in most US and UK homes; RHS H1c) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can candle plant 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 candle plant 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.