Cold hardiness & minimum temperature

Is Shining Temple Bells (Smithiantha fulgida)cold hardy? Hardiness zone & min temp

Also called Shining Temple Bells, Brilliant Temple Bells.

More about shining temple bells

About Shining Temple Bells

Smithiantha fulgida · also called Shining Temple Bells, Brilliant Temple Bells · flowering

Smithiantha fulgida is treated in current trade and cultivation as the bold, scarlet-flowered form of the cinnabarina complex — a compact rhizomatous gesneriad with plain green, velvet-hairy leaves that take on a maroon sheen in good light, and brilliant vermilion tubular flowers in autumn. Grow identically to other Smithianthas: bright indirect light, high humidity, and a dry winter rest.

Cold limit: USDA 11–12 · RHS H1a (18–25°C (growing); 10–12°C (dormancy))

Watch for — Rhizome rot during dormancy: Continuing to water through winter in a cold room leads to rhizome rot. Once foliage has fully died back, store rhizomes dry or barely moist at 10–12°C until spring.

What shining temple bells's hardiness rating actually means

Shining Temple Bells 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 H1a means: Tropical — needs a heated room or greenhouse; no frost tolerance whatsoever. On the US scale that maps to USDA 11–12 — 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 above about 15 °C (warm, never cold). Shining Temple Bells has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for shining temple bells as it gets too cold:

Below about above about 15 °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 shining temple bells go outside or overwinter — and where?

It can holiday outdoors in summer once nights are reliably above above 15 °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 shining temple bells can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1a figure above.

Shining Temple Bells hardiness — frequently asked questions

Is shining temple bells cold hardy?

Shining Temple Bells 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. Shining Temple Bells can only live outside year-round in genuinely frost-free climates (roughly USDA 11–12); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature shining temple bells can survive?

Minimum survivable temperature is roughly above about 15 °C (warm, never cold). Shining Temple Bells has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

What hardiness zone is shining temple bells?

Shining Temple Bells is rated USDA 11–12 and RHS H1a — Tropical — needs a heated room or greenhouse; no frost tolerance whatsoever.

Can shining temple bells survive winter outside?

It can holiday outdoors in summer once nights are reliably above above 15 °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 shining temple bells below its minimum temperature?

Below about above about 15 °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.