Cold hardiness & minimum temperature

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

Also called blistered begonia, pimpled begonia.

More about begonia pustulata

About Begonia pustulata

Begonia pustulata · also called blistered begonia, pimpled begonia · houseplant

Begonia pustulata is a low, creeping rhizomatous species from Central America grown for puckered, blistered leaves of deep velvety green netted with silver veins. It loves warm, shaded, very humid spots and thrives in terrariums. Keep the airy mix lightly moist, set the rhizome at the surface, and avoid wetting the bumpy leaves, which rot easily.

Cold limit: USDA 10-11 (grown indoors in most of the US and UK) · RHS H1b (18-26°C)

What begonia pustulata's hardiness rating actually means

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

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

Begonia pustulata hardiness — frequently asked questions

Is begonia pustulata cold hardy?

Begonia pustulata 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 pustulata 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 pustulata can survive?

What hardiness zone is begonia pustulata?

Begonia pustulata 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 pustulata 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 pustulata 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.