Cold hardiness & minimum temperature

Is Polka Dot Begonia (Begonia maculata 'Wightii')cold hardy? Hardiness zone & min temp

Also called Spotted Begonia, Angel Wing Begonia.

More about polka dot begonia

About Polka Dot Begonia

Begonia maculata 'Wightii' · also called Spotted Begonia, Angel Wing Begonia · houseplant

Polka Dot Begonia is a cane-type begonia famous for olive-green angel-wing leaves dotted with silver spots and a deep red underside. Upright and fast-growing, it wants bright indirect light, even moisture, and decent humidity, and rewards good care with clusters of white flowers. Striking but toxic to pets, so site it out of their reach.

Cold limit: USDA 10-11 (indoor in most US and UK homes) · RHS H1b (18-26°C)

What polka dot begonia's hardiness rating actually means

Polka Dot Begonia 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 (indoor in most US and UK 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 10 °C (sustained cold below this is damaging). Polka Dot Begonia has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Polka Dot Begonia hardiness — frequently asked questions

Is polka dot begonia cold hardy?

Polka Dot Begonia 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. Polka Dot Begonia can only live outside year-round in genuinely frost-free climates (roughly USDA 10-11 (indoor in most US and UK homes)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature polka dot begonia can survive?

What hardiness zone is polka dot begonia?

Polka Dot Begonia is rated USDA 10-11 (indoor in most US and UK homes) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can polka dot begonia 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 polka dot begonia 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.