Cold hardiness & minimum temperature

Is Thomsonii Wax Plant (Hoya thomsonii)cold hardy? Hardiness zone & min temp

Also called Thomsonii Wax Plant, Fuzzy-leaf Hoya, Thomson's Hoya.

More about thomsonii wax plant

About Thomsonii Wax Plant

Hoya thomsonii · also called Thomsonii Wax Plant, Fuzzy-leaf Hoya · houseplant

Hoya thomsonii is a slow-growing epiphytic vine from the Himalayan foothills, prized for velvety, fine-haired leaves and fragrant white-cream star flowers. Give it bright indirect light, let the mix dry between waterings, and use an airy bark-based blend. The wider Hoya genus is ASPCA non-toxic, so it is generally pet-safe.

Cold limit: USDA 10-11 (grown as a houseplant elsewhere) (16-24°C (keep above 10°C))

Watch for — No flowers: Insufficient light, cold drafts or lack of nutrients hold back blooms. Give bright indirect light, feed with a higher-phosphorus fertiliser in spring/summer, and never cut off old peduncles.

What thomsonii wax plant's hardiness rating actually means

Thomsonii Wax Plant 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 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). Thomsonii Wax Plant has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Thomsonii Wax Plant hardiness — frequently asked questions

Is thomsonii wax plant cold hardy?

Thomsonii Wax Plant 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. Thomsonii Wax Plant can only live outside year-round in genuinely frost-free climates (roughly USDA 10-11 (grown as a houseplant elsewhere)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature thomsonii wax plant can survive?

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

What hardiness zone is thomsonii wax plant?

Thomsonii Wax Plant is rated USDA 10-11 (grown as a houseplant elsewhere) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can thomsonii wax plant 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 thomsonii wax plant 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.