Cold hardiness & minimum temperature

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

Also called fern begonia, foliosa begonia, feathery begonia.

More about begonia foliosa

About Begonia foliosa

Begonia foliosa · also called fern begonia, foliosa begonia · houseplant

Begonia foliosa, the fern begonia, is a shrub-like species from the Colombian and Venezuelan Andes with arching stems densely lined by tiny glossy leaves that mimic a fern or maidenhair frond. It carries small pendant pink-to-white flowers and makes a graceful, fine-textured houseplant or basket subject that appreciates cool, humid, bright-but-shaded conditions.

Cold limit: USDA 10-11 (indoors in most US and UK homes) · RHS H1B (16-24°C)

Watch for — Root rot: Cold, soggy compost rots the fibrous roots. Let the surface dry slightly between waterings and ensure free drainage.

What begonia foliosa's hardiness rating actually means

Begonia foliosa 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 10-11 (indoors 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 5 °C (and never frost). Begonia foliosa has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Begonia foliosa hardiness — frequently asked questions

Is begonia foliosa cold hardy?

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

What is the minimum temperature begonia foliosa can survive?

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

What hardiness zone is begonia foliosa?

Begonia foliosa is rated USDA 10-11 (indoors in most US and UK homes) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can begonia foliosa 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 begonia foliosa 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.