Cold hardiness & minimum temperature

Is Boea Hygroscopica (Boea hygroscopica)cold hardy? Hardiness zone & min temp

Also called resurrection plant, Boea.

More about boea hygroscopica

About Boea Hygroscopica

Boea hygroscopica · also called resurrection plant, Boea · houseplant

Boea hygroscopica is a rosette-forming gesneriad from Southeast Asia, prized as a 'resurrection plant' for its ability to dry out completely and revive when rewatered. Indoors it wants warm, humid, shaded conditions like its African violet relatives, with airy soil and gentle watering. Its ASPCA pet-safety status is undocumented, so keep it away from pets.

Cold limit: USDA 10-11 (indoor in most US homes) (18-26°C)

What boea hygroscopica's hardiness rating actually means

Boea Hygroscopica 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 H1c means: Warm-temperate — can summer outdoors but must come in well before the first frost. On the US scale that maps to USDA 10-11 (indoor 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 5 °C (and never frost). Boea Hygroscopica has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for boea hygroscopica as it gets too cold:

Below about about 5 °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 boea hygroscopica go outside or overwinter — and where?

It can holiday outdoors in summer once nights are reliably above 5 °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 boea hygroscopica can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c figure above.

Boea Hygroscopica hardiness — frequently asked questions

Is boea hygroscopica cold hardy?

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

What is the minimum temperature boea hygroscopica can survive?

Minimum survivable temperature is roughly about 5 °C (and never frost). Boea Hygroscopica has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

What hardiness zone is boea hygroscopica?

Boea Hygroscopica is rated USDA 10-11 (indoor in most US homes) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can boea hygroscopica survive winter outside?

It can holiday outdoors in summer once nights are reliably above 5 °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 boea hygroscopica below its minimum temperature?

Below about about 5 °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.