Cold hardiness & minimum temperature

Is Ivory Primulina (Primulina eburnea)cold hardy? Hardiness zone & min temp

Also called Ivory Primulina, Ivory Chirita.

More about ivory primulina

About Ivory Primulina

Primulina eburnea · also called Ivory Primulina, Ivory Chirita · flowering

Primulina eburnea is an evergreen, rosette-forming gesneriad with the widest natural distribution in its genus, found on mossy limestone karst cliffs and rock faces across southern China and northern Vietnam. The plant produces soft, hairy leaves and elegant tubular flowers with pale lavender to ivory tubes, darker insides, and a yellow throat. It is described as underrepresented in cultivation despite its handsome blooms and easy temperament. As with other Primulina species, it is not listed on the ASPCA toxic plant database, so it should be classified as mildly-toxic as a precaution.

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

What ivory primulina's hardiness rating actually means

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

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

Ivory Primulina hardiness — frequently asked questions

Is ivory primulina cold hardy?

Ivory Primulina 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. Ivory Primulina 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 ivory primulina can survive?

What hardiness zone is ivory primulina?

Ivory Primulina 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 ivory primulina 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 ivory primulina 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.