Cold hardiness & minimum temperature

Is Begonia carolineifolia (Begonia carolineifolia)cold hardy? Hardiness zone & min temp

Also called palm-leaf rhizomatous begonia, carolineifolia begonia.

More about begonia carolineifolia

About Begonia carolineifolia

Begonia carolineifolia · also called palm-leaf rhizomatous begonia, carolineifolia begonia · houseplant

Begonia carolineifolia is a bold Mexican rhizomatous species with thick, creeping rhizomes and large palmate leaves split into finger-like leaflets, giving an unusual palm-leaf look. It makes an architectural houseplant in warm, bright, humid rooms. Keep the airy mix lightly moist, set the chunky rhizome at the surface, and water at the base to prevent rot.

Cold limit: USDA 10-11 (grown indoors in most of the US and UK) · RHS H1b (18-27°C)

What begonia carolineifolia's hardiness rating actually means

Begonia carolineifolia 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 10-11 (grown indoors in most of the US and UK) — 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). Begonia carolineifolia has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Begonia carolineifolia hardiness — frequently asked questions

Is begonia carolineifolia cold hardy?

Begonia carolineifolia 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. Begonia carolineifolia can only live outside year-round in genuinely frost-free climates (roughly USDA 10-11 (grown indoors in most of the US and UK)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature begonia carolineifolia can survive?

What hardiness zone is begonia carolineifolia?

Begonia carolineifolia is rated USDA 10-11 (grown indoors in most of the US and UK) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can begonia carolineifolia 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 begonia carolineifolia 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.