Cold hardiness & minimum temperature

Is Kalanchoe (Kalanchoe blossfeldiana)cold hardy? Hardiness zone & min temp

Also called flaming Katy, Christmas kalanchoe, Madagascar widow’s thrill.

About Kalanchoe

Kalanchoe blossfeldiana · also called flaming Katy, Christmas kalanchoe · flowering

Kalanchoe is a compact succulent from Madagascar grown for its clusters of small red, pink, yellow or orange flowers. It blooms in winter and lasts for weeks, making it a popular gift plant. Toxic to pets.

Kalanchoe blossfeldiana (Flaming Katy) is a succulent native to Madagascar, adapted to bright, warm conditions with marked dry periods, which is why it stores water in its thick, fleshy leaves.

A compact, mounding succulent grown for dense clusters of small four-petaled flowers in red, pink, orange, yellow or white that can last several weeks; cool nights of around 45-65 F prolong the bloom.

Cold limit: USDA 10-12 (indoor-only in most US homes) · RHS H1c (15-24°C)

Sources: aspca.org, plants.ces.ncsu.edu, hgic.clemson.edu

What kalanchoe's hardiness rating actually means

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

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

Kalanchoe hardiness — frequently asked questions

Is kalanchoe cold hardy?

Kalanchoe 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. Kalanchoe 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 kalanchoe can survive?

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

What hardiness zone is kalanchoe?

Kalanchoe 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 kalanchoe 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 kalanchoe 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.