Cold hardiness & minimum temperature

Is Rough-Leaf Begonia (Begonia muricata)cold hardy? Hardiness zone & min temp

Also called Rough-Leaf Begonia, Prickly Begonia.

More about rough-leaf begonia

About Rough-Leaf Begonia

Begonia muricata · also called Rough-Leaf Begonia, Prickly Begonia · houseplant

Begonia muricata is a distinctive fibrous-rooted species noted for its rough, textured leaf surfaces bearing small wart-like protuberances, native to tropical regions of Africa or South America depending on taxonomic authority. It grows best in warm, humid indoor conditions with bright indirect light and well-draining compost. The single most important care fact is that the rough foliage should not be misted directly, as moisture trapped in the surface texture promotes fungal disease. All begonias, including this species, are toxic to cats and dogs.

Cold limit: USDA 10-12 (indoor in most climates) · RHS H1b (13–24 °C)

What rough-leaf begonia's hardiness rating actually means

Rough-Leaf 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 10-12 (indoor in most climates) — 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). Rough-Leaf Begonia has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Rough-Leaf Begonia hardiness — frequently asked questions

Is rough-leaf begonia cold hardy?

Rough-Leaf 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. Rough-Leaf Begonia can only live outside year-round in genuinely frost-free climates (roughly USDA 10-12 (indoor in most climates)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature rough-leaf begonia can survive?

What hardiness zone is rough-leaf begonia?

Rough-Leaf Begonia is rated USDA 10-12 (indoor in most climates) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can rough-leaf 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 rough-leaf 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.