Cold hardiness & minimum temperature

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

Also called Scortechinii Hoya.

More about hoya scortechinii

About Hoya Scortechinii

Hoya scortechinii · also called Scortechinii Hoya · houseplant

Hoya scortechinii is a Southeast Asian epiphytic wax plant from Malaysia and Borneo, grown for slender twining vines, elongated green leaves and showy clusters of fuzzy, brightly coloured star flowers. It follows classic Hoya care: bright indirect light, a fast-draining epiphytic mix and a thorough dry-down between waterings, rewarding patience with fragrant, long-lasting blooms.

Cold limit: USDA 10-12 (indoor in most US homes) · RHS H1b (18-29°C)

What hoya scortechinii's hardiness rating actually means

Hoya Scortechinii 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 10-12 (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 10 °C (sustained cold below this is damaging). Hoya Scortechinii has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Hoya Scortechinii hardiness — frequently asked questions

Is hoya scortechinii cold hardy?

Hoya Scortechinii 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 Scortechinii can only live outside year-round in genuinely frost-free climates (roughly USDA 10-12 (indoor in most US homes)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature hoya scortechinii can survive?

What hardiness zone is hoya scortechinii?

Hoya Scortechinii is rated USDA 10-12 (indoor in most US homes) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can hoya scortechinii 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 scortechinii 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.