Cold hardiness & minimum temperature

Is Bell Cotyledon (Cotyledon campanulata)cold hardy? Hardiness zone & min temp

Also called Bell Cotyledon.

More about bell cotyledon

About Bell Cotyledon

Cotyledon campanulata · also called Bell Cotyledon · houseplant

A rare, upright South African succulent with cylindrical, grey-green leaves and distinctive tubular, bell-shaped red-orange flowers. Less commonly cultivated than Cotyledon orbiculata but equally striking when in bloom. Needs the same bright, dry conditions and infrequent watering as other Cotyledon. Best suited to experienced succulent growers.

Cold limit: USDA 10–11 · RHS H1c (10–30°C)

What bell cotyledon's hardiness rating actually means

Bell Cotyledon 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 — 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). Bell Cotyledon has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for bell cotyledon 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 bell cotyledon 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 bell cotyledon can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c figure above.

Bell Cotyledon hardiness — frequently asked questions

Is bell cotyledon cold hardy?

Bell Cotyledon 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. Bell Cotyledon can only live outside year-round in genuinely frost-free climates (roughly USDA 10–11); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature bell cotyledon can survive?

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

What hardiness zone is bell cotyledon?

Bell Cotyledon is rated USDA 10–11 and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can bell cotyledon 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 bell cotyledon 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.