Cold hardiness & minimum temperature

Is Kohleria (Kohleria eriantha)cold hardy? Hardiness zone & min temp

Also called tree gloxinia, Kohleria, kohleria.

More about kohleria

About Kohleria

Kohleria eriantha · also called tree gloxinia, Kohleria · flowering

Kohleria eriantha is a tropical rhizomatous gesneriad with velvety, softly hairy leaves and clusters of tubular red-orange flowers freckled with yellow inside. A relative of the African violet, it flowers prolifically in warmth and bright indirect light, then rests by dying back to scaly underground rhizomes. Easy and forgiving once you respect its dormancy, it suits pots and hanging displays alike.

Cold limit: USDA 10-11 (indoor in most US and UK homes; frost-tender) · RHS H1b (18-27°C)

Watch for — Leaf spotting and marks: Cold water or droplets sitting on the hairy leaves cause pale or brown blotches. Water at the soil with tepid water and avoid wetting the foliage.

What kohleria's hardiness rating actually means

Kohleria 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 10-11 (indoor in most US and UK homes; frost-tender) — 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). Kohleria has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Kohleria hardiness — frequently asked questions

Is kohleria cold hardy?

Kohleria 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. Kohleria can only live outside year-round in genuinely frost-free climates (roughly USDA 10-11 (indoor in most US and UK homes; frost-tender)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature kohleria can survive?

Minimum survivable temperature is roughly about 10 °C (sustained cold below this is damaging). Kohleria has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

What hardiness zone is kohleria?

Kohleria is rated USDA 10-11 (indoor in most US and UK homes; frost-tender) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can kohleria 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 kohleria 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.