Cold hardiness & minimum temperature

Is Warming's Sinningia (Sinningia warmingii)cold hardy? Hardiness zone & min temp

Also called Warming's Sinningia.

More about warming's sinningia

About Warming's Sinningia

Sinningia warmingii · also called Warming's Sinningia · flowering

Sinningia warmingii is a tuberous gesneriaceae species native to the tropical and subtropical montane forests of Brazil, named in honour of the Danish botanist Eugen Warming. It produces distinctive tubular yellow flowers striped with red, making it a striking collector's species that performs well as an indoor or conservatory plant. As with all tuberous Sinningia, the plant enters a winter dormancy and must be kept dry during that period to prevent tuber rot. Sinningia species are considered non-toxic to cats and dogs by the ASPCA.

Cold limit: USDA 9b-11 · RHS H1c (14–26°C)

Watch for — Tuber rot in winter: Leaving dormant tubers in moist compost in cool temperatures is the most common cause of plant loss; store completely dry in a cool but frost-free spot (minimum 12°C).

What warming's sinningia's hardiness rating actually means

Warming's 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 9b-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). Warming's Sinningia has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Warming's Sinningia hardiness — frequently asked questions

Is warming's sinningia cold hardy?

Warming's 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. Warming's Sinningia can only live outside year-round in genuinely frost-free climates (roughly USDA 9b-11); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature warming's sinningia can survive?

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

What hardiness zone is warming's sinningia?

Warming's Sinningia is rated USDA 9b-11 and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can warming's 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 warming's 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.