Cold hardiness & minimum temperature

Is Sellow's Sinningia (Sinningia sellovii)cold hardy? Hardiness zone & min temp

Also called Sellow's Sinningia, Hardy Red Gloxinia, Hardy Gloxinia.

More about sellow's sinningia

About Sellow's Sinningia

Sinningia sellovii · also called Sellow's Sinningia, Hardy Red Gloxinia · flowering

Sinningia sellovii is a tuberous perennial native to Brazil, Bolivia, Paraguay, and Uruguay, where it grows in rocky, open habitats. It produces tubular red to orange-red flowers attractive to hummingbirds and is one of the hardiest Sinningia species, tolerating light frost when its tuber is established in the ground. Allow the tuber to dry out and go dormant in cooler months — do not water during dormancy or the tuber will rot. According to the ASPCA, Sinningia species (closely related to Gloxinia) are listed as non-toxic to cats and dogs.

Cold limit: USDA 7b-11 · RHS H3 (10–27°C)

What sellow's sinningia's hardiness rating actually means

Sellow's Sinningia is half-hardy (RHS H3). It survives a mild winter outdoors in a sheltered spot, but a hard frost kills it — so in colder zones it is lifted, potted, or grown as a tender plant. Its RHS rating of H3 means: Half-hardy — comes through mild UK winters outside but is killed by a hard freeze. On the US scale that maps to USDA 7b-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 to 1 °C — a light, short frost only. Sellow's Sinningia shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for sellow's sinningia as it gets too cold:

Down to roughly about −5 to 1 °C it copes, especially if dry and sheltered.
A sustained hard frost collapses the top growth; whether it returns depends on whether the roots, crown or tubers froze.
Wet cold is far more lethal than dry cold for this plant — soggy, frozen soil is the usual killer.

Can sellow's sinningia go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 7b-11 or a frost-free UK microclimate.
In colder zones, grow it in a pot you can move under cover, or lift its tubers/roots and store them frost-free over winter.
A south-facing wall, free-draining soil and a dry winter position can push it a full zone hardier than the books suggest.

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 sellow's sinningia can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H3 figure above.

Frost protection for borderline sellow's sinningia

Sellow's Sinningia is right on a hardiness edge in many gardens, so if you are pushing it, these measures buy it the margin it needs:

Mulch the crown or root zone deeply with bark, straw or leaf-mould before the first hard frost.
Move container plants against a warm wall or into an unheated but frost-free porch or greenhouse.
Fleece the top growth on the coldest nights, and keep it on the dry side — dry roots survive cold far better than wet ones.
Lift dahlia-type tubers or tender crowns after the first light frost blackens the foliage and store them somewhere cool but frost-free.

Sellow's Sinningia hardiness — frequently asked questions

Is sellow's sinningia cold hardy?

Sellow's Sinningia is half-hardy (RHS H3). It survives a mild winter outdoors in a sheltered spot, but a hard frost kills it — so in colder zones it is lifted, potted, or grown as a tender plant. Borderline outdoors. In its mild end of USDA 7b-11 (and sheltered UK gardens) sellow's sinningia can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

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

Minimum survivable temperature is roughly about −5 to 1 °C — a light, short frost only. Sellow's Sinningia shrugs off cold nights but a real, sustained freeze will kill it.

What hardiness zone is sellow's sinningia?

Sellow's Sinningia is rated USDA 7b-11 and RHS H3 — Half-hardy — comes through mild UK winters outside but is killed by a hard freeze.

Can sellow's sinningia survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 7b-11 or a frost-free UK microclimate. In colder zones, grow it in a pot you can move under cover, or lift its tubers/roots and store them frost-free over winter. A south-facing wall, free-draining soil and a dry winter position can push it a full zone hardier than the books suggest.

How do I protect sellow's sinningia from frost?

Mulch the crown or root zone deeply with bark, straw or leaf-mould before the first hard frost. Move container plants against a warm wall or into an unheated but frost-free porch or greenhouse. Fleece the top growth on the coldest nights, and keep it on the dry side — dry roots survive cold far better than wet ones. Lift dahlia-type tubers or tender crowns after the first light frost blackens the foliage and store them somewhere cool but frost-free.