Cold hardiness & minimum temperature

Is Hoya polyneura (Fishtail Hoya) (Hoya polyneura)cold hardy? Hardiness zone & min temp

Also called Fishtail Hoya, Fishtail Wax Plant, Mermaid Tail Hoya.

More about hoya polyneura (fishtail hoya)

About Hoya polyneura (Fishtail Hoya)

Hoya polyneura · also called Fishtail Hoya, Fishtail Wax Plant · houseplant

Hoya polyneura, the Fishtail Hoya, is an epiphytic wax plant from high-altitude Himalayan forests, prized for thin leaves veined like fish bones. It wants bright indirect light, a well-draining mix that dries slightly between waterings, cool nights and moderate humidity. The ASPCA lists no Hoya as toxic, so it is considered pet-safe.

Cold limit: USDA 10-11 (grown as an indoor houseplant in cooler climates) (10-25C)

Watch for — Heat stress: As a high-altitude species it dislikes prolonged heat; temperatures much above ~27C (80F) stress the plant and discourage flowering. Keep it cooler than most tropical hoyas, especially at night.

What hoya polyneura (fishtail hoya)'s hardiness rating actually means

Hoya polyneura (Fishtail Hoya) 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 (grown as an indoor houseplant in cooler 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 5 °C (and never frost). Hoya polyneura (Fishtail Hoya) has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for hoya polyneura (fishtail hoya) 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 hoya polyneura (fishtail hoya) 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 hoya polyneura (fishtail hoya) can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c figure above.

Hoya polyneura (Fishtail Hoya) hardiness — frequently asked questions

Is hoya polyneura (fishtail hoya) cold hardy?

Hoya polyneura (Fishtail Hoya) 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. Hoya polyneura (Fishtail Hoya) can only live outside year-round in genuinely frost-free climates (roughly USDA 10-11 (grown as an indoor houseplant in cooler climates)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature hoya polyneura (fishtail hoya) can survive?

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

What hardiness zone is hoya polyneura (fishtail hoya)?

Hoya polyneura (Fishtail Hoya) is rated USDA 10-11 (grown as an indoor houseplant in cooler climates) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can hoya polyneura (fishtail hoya) 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 hoya polyneura (fishtail hoya) 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.