Cold hardiness & minimum temperature

Is Node-flower Cyanotis (Cyanotis nodiflora)cold hardy? Hardiness zone & min temp

Also called Node-flower Cyanotis.

More about node-flower cyanotis

About Node-flower Cyanotis

Cyanotis nodiflora · also called Node-flower Cyanotis · houseplant

Cyanotis nodiflora is a softly hairy, erect-to-trailing perennial from tropical Asia, producing small blue or pink flowers at the nodes in summer. It shares the family's characteristic hairy stems and preference for bright, indirect light with well-drained, gritty soil and warm temperatures. Avoid misting the foliage.

Cold limit: USDA 10-12 · RHS H1c (18–26°C (min 12°C))

Watch for — Faded foliage colour: Insufficient light causes the purple undersides to fade and growth to become lank. Move to a brighter spot within 60 cm of a window. Supplement with a grow light in winter if needed.

What node-flower cyanotis's hardiness rating actually means

Node-flower Cyanotis 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 10-12 — 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). Node-flower Cyanotis has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Node-flower Cyanotis hardiness — frequently asked questions

Is node-flower cyanotis cold hardy?

Node-flower Cyanotis 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. Node-flower Cyanotis can only live outside year-round in genuinely frost-free climates (roughly USDA 10-12); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature node-flower cyanotis can survive?

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

What hardiness zone is node-flower cyanotis?

Node-flower Cyanotis is rated USDA 10-12 and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can node-flower cyanotis 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 node-flower cyanotis 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.