Cold hardiness & minimum temperature

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

Also called Caudata Sumatra hoya, Sumatra wax plant, wax plant, wax flower.

More about hoya caudata (sumatra)

About Hoya caudata (Sumatra)

Hoya caudata · also called Caudata Sumatra hoya, Sumatra wax plant · tropical

Hoya caudata 'Sumatra' is a slow-growing tropical epiphytic vine prized for thick, silver-flecked leaves with red undersides and fragrant star-shaped flower clusters. Give it bright indirect light, a chunky free-draining mix, 60-80% humidity, and let the soil dry between waterings. The Hoya genus is ASPCA non-toxic, making it pet-safe.

Cold limit: USDA 10-12 (indoor houseplant elsewhere) (18-27 C)

Watch for — Cold or draft damage: Stems and leaves suffer below about 15 C (59 F) and near cold windows, heaters, or AC drafts, keep temperatures stable and warm.

What hoya caudata (sumatra)'s hardiness rating actually means

Hoya caudata (Sumatra) 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 (indoor houseplant elsewhere) — 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 caudata (Sumatra) has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Hoya caudata (Sumatra) hardiness — frequently asked questions

Is hoya caudata (sumatra) cold hardy?

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

What is the minimum temperature hoya caudata (sumatra) can survive?

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

What hardiness zone is hoya caudata (sumatra)?

Hoya caudata (Sumatra) is rated USDA 10-12 (indoor houseplant elsewhere) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can hoya caudata (sumatra) 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 caudata (sumatra) 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.