Cold hardiness & minimum temperature

Is Globe-Flowered Wax Plant (Hoya globulosa)cold hardy? Hardiness zone & min temp

Also called Globe-flowered wax plant, Ball hoya, Himalayan wax plant.

More about globe-flowered wax plant

About Globe-Flowered Wax Plant

Hoya globulosa · also called Globe-flowered wax plant, Ball hoya · tropical

Hoya globulosa is a striking epiphytic wax plant native to the Himalayas and southwestern China (Yunnan), notable for its unusually large, densely packed spherical umbels of waxy, sweetly scented flowers and its broad, somewhat velvety leaves. It tolerates cooler temperatures than many Hoyas and can experience a gentle winter rest. Keep it in bright indirect light with a well-draining bark mix and allow the medium to dry before watering. The ASPCA lists the Hoya genus as non-toxic to cats and dogs.

Cold limit: USDA 10-12 (indoor in most climates) · RHS H1b (15–27 °C)

Watch for — Bud blast in flower: Flower buds drop before opening if the plant is moved, waterlogged, or subjected to cold draughts during bud development. Once buds are visible, keep conditions stable and avoid repositioning the pot.

What globe-flowered wax plant's hardiness rating actually means

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

Concretely, for globe-flowered wax plant 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 globe-flowered wax plant 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 globe-flowered wax plant can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1b figure above.

Globe-Flowered Wax Plant hardiness — frequently asked questions

Is globe-flowered wax plant cold hardy?

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

What is the minimum temperature globe-flowered wax plant can survive?

What hardiness zone is globe-flowered wax plant?

Globe-Flowered Wax Plant is rated USDA 10-12 (indoor in most climates) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can globe-flowered wax plant 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 globe-flowered wax plant 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.