Cold hardiness & minimum temperature

Is Kohleria 'Hannah Roberts' (Kohleria 'Hannah Roberts')cold hardy? Hardiness zone & min temp

Also called Hannah Roberts kohleria.

More about kohleria 'hannah roberts'

About Kohleria 'Hannah Roberts'

Kohleria 'Hannah Roberts' · also called Hannah Roberts kohleria · flowering

Kohleria 'Hannah Roberts' is a popular rhizomatous gesneriad cultivar bearing showy bell-shaped flowers in pink-to-red densely freckled with deeper spots, set against soft hairy green leaves. Growing from scaly water-storing rhizomes that make it forgiving, it flowers over a long season in bright indirect light and warmth, as long as its fuzzy foliage is kept dry.

Cold limit: USDA 10-11 (grown indoors in most US homes) · RHS H1b (18-27°C)

Watch for — Sudden collapse to rhizomes: Usually a natural winter semi-dormancy, not loss of the plant. Keep the rhizomes barely moist and warm and growth restarts in spring.

What kohleria 'hannah roberts''s hardiness rating actually means

Kohleria 'Hannah Roberts' 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 (grown indoors in most US homes) — 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 'Hannah Roberts' has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Kohleria 'Hannah Roberts' hardiness — frequently asked questions

Is kohleria 'hannah roberts' cold hardy?

Kohleria 'Hannah Roberts' 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 'Hannah Roberts' can only live outside year-round in genuinely frost-free climates (roughly USDA 10-11 (grown indoors in most US homes)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature kohleria 'hannah roberts' can survive?

What hardiness zone is kohleria 'hannah roberts'?

Kohleria 'Hannah Roberts' is rated USDA 10-11 (grown indoors in most US homes) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can kohleria 'hannah roberts' 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 'hannah roberts' 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.