Cold hardiness & minimum temperature

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

Also called Clustered Sinningia, Miniature Gloxinia.

More about clustered sinningia

About Clustered Sinningia

Sinningia aggregata · also called Clustered Sinningia, Miniature Gloxinia · flowering

Sinningia aggregata is a tuberous perennial in the family Gesneriaceae, native to the subtropical and highland forests of Paraná, Santa Catarina, and São Paulo states in southern Brazil. It grows to about 30 cm tall, producing branching upright stems with velvety, lemon-scented leaves and clusters of vivid orange-red tubular flowers that attract hummingbirds in the wild. It stores energy in a small tuber and goes dormant in winter, which is entirely normal; the key care rule is to stop watering when dormancy begins and resume only when new growth emerges in spring. According to the ASPCA, Gloxinia (Sinningia speciosa) — the type species of this genus — is non-toxic to dogs, cats, and horses.

Cold limit: USDA 10-12 (indoor in most climates) · RHS H1b (15–26°C)

What clustered sinningia's hardiness rating actually means

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

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

Clustered Sinningia hardiness — frequently asked questions

Is clustered sinningia cold hardy?

Clustered 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. Clustered Sinningia 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 clustered sinningia can survive?

What hardiness zone is clustered sinningia?

Clustered Sinningia 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 clustered sinningia 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 clustered sinningia 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.