Cold hardiness & minimum temperature

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

Also called Wax plant, Porcelain flower, Pink silver vine, Silver pink vine.

More about hoya pubicalyx

About Hoya pubicalyx

Hoya pubicalyx · also called Wax plant, Porcelain flower · tropical

Hoya pubicalyx is a fast-growing, semi-succulent climbing wax plant from the Philippine rainforest, prized for its silver-flecked leaves and fragrant clusters of star-shaped pink-to-near-black flowers. Its one defining care need is restraint with water: the thick, water-storing leaves rot quickly if the mix stays wet, so let it dry well between drinks.

Cold limit: USDA 10a-11b · RHS H1B (min 10-15°C; grow under glass / as a houseplant in the UK) (16-29°C)

What hoya pubicalyx's hardiness rating actually means

Hoya pubicalyx 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 10a-11b — 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). Hoya pubicalyx has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Hoya pubicalyx hardiness — frequently asked questions

Is hoya pubicalyx cold hardy?

Hoya pubicalyx 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 pubicalyx can only live outside year-round in genuinely frost-free climates (roughly USDA 10a-11b); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature hoya pubicalyx can survive?

What hardiness zone is hoya pubicalyx?

Hoya pubicalyx is rated USDA 10a-11b and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can hoya pubicalyx 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 hoya pubicalyx 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.