Cold hardiness & minimum temperature

Is Hoya Krimson Queen (Hoya carnosa 'Krimson Queen')cold hardy? Hardiness zone & min temp

Also called Krimson Queen wax plant, variegated wax plant, Krimson Queen hoya, porcelain flower.

More about hoya krimson queen

About Hoya Krimson Queen

Hoya carnosa 'Krimson Queen' · also called Krimson Queen wax plant, variegated wax plant · houseplant

The Hoya Krimson Queen is a variegated wax plant cultivar with creamy-white leaf margins and pink-flushed new growth, grown as a trailing or climbing vine. Give it bright indirect light, water only when the soil dries, and it stays easygoing. ASPCA lists Hoya carnosa as non-toxic to cats and dogs, making it pet-friendly.

Cold limit: USDA 10-12 (outdoors); grown as a houseplant elsewhere (16-29°C)

What hoya krimson queen's hardiness rating actually means

Hoya Krimson Queen 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 (outdoors); grown as a 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 Krimson Queen has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Hoya Krimson Queen hardiness — frequently asked questions

Is hoya krimson queen cold hardy?

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

What is the minimum temperature hoya krimson queen can survive?

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

What hardiness zone is hoya krimson queen?

Hoya Krimson Queen is rated USDA 10-12 (outdoors); grown as a houseplant elsewhere and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can hoya krimson queen 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 krimson queen 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.