Cold hardiness & minimum temperature

Is Hoya Lobbii (Hoya lobbii)cold hardy? Hardiness zone & min temp

Also called Lobb's Hoya, Lobbii Wax Plant.

More about hoya lobbii

About Hoya Lobbii

Hoya lobbii · also called Lobb's Hoya, Lobbii Wax Plant · houseplant

Hoya lobbii is a striking species prized for large, deep-red to crimson star flowers with reflexed petals and a contrasting coronet. Leaves are thick, oval and often veined. It blooms readily for a Hoya, rewarding bright light and a lean, fast-draining mix with eye-catching, sometimes fragrant flower umbels.

Cold limit: USDA 10-12 (indoor in most US homes) · RHS H1b (18-28°C)

Watch for — Bud drop: Forming buds abort after sudden environmental changes or erratic watering. Keep light, temperature and moisture steady once a peduncle develops, and don't relocate the plant.

What hoya lobbii's hardiness rating actually means

Hoya Lobbii 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 Lobbii has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Hoya Lobbii hardiness — frequently asked questions

Is hoya lobbii cold hardy?

Hoya Lobbii 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 Lobbii 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 lobbii can survive?

Minimum survivable temperature is roughly about 10 °C (sustained cold below this is damaging). Hoya Lobbii has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

What hardiness zone is hoya lobbii?

Hoya Lobbii 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 lobbii 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 lobbii 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.