Cold hardiness & minimum temperature

Is orange sinningia (Sinningia aggregata)cold hardy? Hardiness zone & min temp

Also called orange sinningia, miniature gloxinia.

More about orange sinningia

About orange sinningia

Sinningia aggregata · also called orange sinningia, miniature gloxinia · flowering

A compact Brazilian tuberous gesneriad producing clusters of vivid orange-red tubular flowers freely over summer above sticky, lemony-scented foliage. Naturally goes dormant in winter, retreating to its underground tuber before re-sprouting in spring. Ideal for bright windowsills and conservatories; Sinningia speciosa (genus type) is listed as non-toxic by ASPCA.

Cold limit: USDA 9–11 · RHS H1c (15–28°C)

Watch for — Tuber rot during dormancy: If the tuber is kept too wet over winter while dormant, it quickly rots. Once leaves die back in autumn, stop all watering and store the pot dry in a cool (10–15°C), dark spot until new growth emerges in spring.

What orange sinningia's hardiness rating actually means

orange sinningia 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 9–11 — 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). orange sinningia has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

orange sinningia hardiness — frequently asked questions

Is orange sinningia cold hardy?

orange sinningia 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. orange sinningia can only live outside year-round in genuinely frost-free climates (roughly USDA 9–11); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature orange sinningia can survive?

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

What hardiness zone is orange sinningia?

orange sinningia is rated USDA 9–11 and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can orange sinningia 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 orange sinningia 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.