Cold hardiness & minimum temperature

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

Also called Eyelash Begonia, Eyelash-leaf Begonia, Miniature Eyelash Begonia.

More about eyelash begonia

About Eyelash Begonia

Begonia bowerae · also called Eyelash Begonia, Eyelash-leaf Begonia · houseplant

The eyelash begonia is a compact, rhizomatous foliage houseplant prized for emerald leaves edged with chocolate markings and fine "eyelash" hairs. It wants bright indirect light, consistently-but-not-soggy moist soil, and high humidity around 50 to 70 percent. The ASPCA lists Begonia as toxic to cats and dogs, so keep it out of reach.

Cold limit: USDA 10-11 (tender; grown as a houseplant elsewhere) (18-24°C)

Watch for — Powdery mildew: Begonias are prone to this white, dusty fungal coating on leaves, encouraged by damp foliage, cool temperatures and poor airflow. Avoid wetting the leaves, improve air circulation, and remove affected foliage promptly.

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 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 (tender; grown as a houseplant elsewhere) — 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). 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 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 eyelash begonia 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 eyelash begonia can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c 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 10-11 (tender; grown as a houseplant elsewhere)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature eyelash begonia can survive?

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

What hardiness zone is eyelash begonia?

Eyelash Begonia is rated USDA 10-11 (tender; grown as a houseplant elsewhere) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can eyelash begonia 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 eyelash begonia 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.