Cold hardiness & minimum temperature

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

Also called Eyelash begonia, Miniature eyelash begonia.

More about eyelash begonia

About Eyelash Begonia

Begonia bowerae · also called Eyelash begonia, Miniature eyelash begonia · houseplant

Begonia bowerae is a compact rhizomatous perennial native to the humid forests of Oaxaca and Chiapas in southern Mexico, prized for its small, heart-shaped, emerald-green leaves decorated with chocolate-brown markings and distinctive white bristles (the 'eyelashes') along the leaf margins. In late winter to early spring it produces loose clusters of pale pink to white flowers above the foliage. It is one of the easier begonias for home growers, tolerating medium light and modest humidity better than many species. Toxic to cats, dogs, and horses.

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

What eyelash begonia's hardiness rating actually means

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

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

Eyelash Begonia hardiness — frequently asked questions

Is eyelash begonia cold hardy?

Eyelash 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. Eyelash 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 eyelash begonia can survive?

What hardiness zone is eyelash begonia?

Eyelash 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 eyelash 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 eyelash 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.