Cold hardiness & minimum temperature

Is Stained Glass Begonia (Begonia 'Stained Glass')cold hardy? Hardiness zone & min temp

Also called Stained Glass begonia, Stained Glass rex begonia.

More about stained glass begonia

About Stained Glass Begonia

Begonia 'Stained Glass' · also called Stained Glass begonia, Stained Glass rex begonia · houseplant

Begonia 'Stained Glass' is a rex-type cultorum hybrid prized for its extraordinary foliage: large, silvery leaves with bold emerald-green veining, deep burgundy-red undersides, and near-translucent zones between the veins that recall a cathedral window in bright light. It is a purely ornamental foliage plant that demands stable warmth, bright indirect light, and elevated humidity, while remaining intolerant of temperature fluctuations and draughts. The most important care rule is to keep humidity consistently above 60% without wetting the leaf surface, as water spots can damage the delicate, thin-textured leaves. Toxic to cats and dogs per the ASPCA.

Cold limit: USDA 10-12 (indoor in most climates) · RHS H1b (18–26 °C)

Watch for — Botrytis (grey mould) in cool, damp conditions: Cool temperatures combined with high humidity and poor air movement create ideal conditions for Botrytis cinerea; maintain temperatures above 18 °C, provide gentle air circulation, and promptly remove any dying leaves.

What stained glass begonia's hardiness rating actually means

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

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

Stained Glass Begonia hardiness — frequently asked questions

Is stained glass begonia cold hardy?

Stained Glass 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. Stained Glass 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 stained glass begonia can survive?

What hardiness zone is stained glass begonia?

Stained Glass 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 stained glass 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 stained glass 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.