Cold hardiness & minimum temperature

Is Queen of the Night (Selenicereus grandiflorus)cold hardy? Hardiness zone & min temp

Also called Large-Flowered Cactus, Sweet-Scented Cactus, Night-Blooming Cereus.

More about queen of the night

About Queen of the Night

Selenicereus grandiflorus · also called Large-Flowered Cactus, Sweet-Scented Cactus · flowering

Selenicereus grandiflorus is a sprawling, vining cactus from the Caribbean and Mexico, famous for producing the largest and most intensely fragrant cactus flowers in the world — up to 30 cm wide — which open for a single night only. A dramatic flowering specimen for a bright, warm room. Needs support as it sprawls extensively. Generally pet-safe as a true cactus.

Cold limit: USDA 10-12 (indoor-only in the UK and most of the US) · RHS H1c (15-32°C)

Watch for — Failure to bloom: Flowering requires a cool, dry winter rest (15-18°C), followed by warmth and consistent moisture in spring. Also needs mature stems — young plants rarely bloom.

What queen of the night's hardiness rating actually means

Queen of the Night 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-only in the UK and most of the US) — 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). Queen of the Night has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Queen of the Night hardiness — frequently asked questions

Is queen of the night cold hardy?

Queen of the Night 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. Queen of the Night can only live outside year-round in genuinely frost-free climates (roughly USDA 10-12 (indoor-only in the UK and most of the US)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature queen of the night can survive?

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

What hardiness zone is queen of the night?

Queen of the Night is rated USDA 10-12 (indoor-only in the UK and most of the US) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can queen of the night 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 queen of the night 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.