Cold hardiness & minimum temperature

Is Brazilian Plume Flower (Justicia carnea)cold hardy? Hardiness zone & min temp

Also called Brazilian Plume, Flamingo Flower, Pink Jacobinia, King's Crown.

More about brazilian plume flower

About Brazilian Plume Flower

Justicia carnea · also called Brazilian Plume, Flamingo Flower · houseplant

Justicia carnea is an evergreen tropical shrub from South America prized for its dramatic, feathery pink or magenta flower plumes in summer and autumn. It thrives in bright indirect light with consistent moisture. Grows 60–120 cm indoors. Not listed as toxic by the ASPCA, generally considered safe around pets.

Cold limit: USDA 10-11 (indoor-only below zone 10) · RHS H1C (16-27°C)

What brazilian plume flower's hardiness rating actually means

Brazilian Plume Flower 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-only below zone 10) — 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). Brazilian Plume Flower has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for brazilian plume flower 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 brazilian plume flower 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 brazilian plume flower can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c figure above.

Brazilian Plume Flower hardiness — frequently asked questions

Is brazilian plume flower cold hardy?

Brazilian Plume Flower 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. Brazilian Plume Flower can only live outside year-round in genuinely frost-free climates (roughly USDA 10-11 (indoor-only below zone 10)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature brazilian plume flower can survive?

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

What hardiness zone is brazilian plume flower?

Brazilian Plume Flower is rated USDA 10-11 (indoor-only below zone 10) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can brazilian plume flower 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 brazilian plume flower 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.