Cold hardiness & minimum temperature

Is Lady of the Night (Brunfelsia americana)cold hardy? Hardiness zone & min temp

Also called Lady of the Night, American Brunfelsia, Raintree.

More about lady of the night

About Lady of the Night

Brunfelsia americana · also called Lady of the Night, American Brunfelsia · tropical

Lady of the Night is a tropical shrub in the nightshade family, grown for its creamy-white to pale yellow tubular flowers that release an intoxicating vanilla-like fragrance exclusively after dusk. It blooms prolifically in warm climates in full sun to part shade. All parts are severely toxic to pets and humans. Hardy outdoors in USDA zones 9–11.

Cold limit: USDA 9-11 · RHS H1b (10–35°C)

Watch for — Bud drop from environmental stress: Flower buds fall before opening when the plant is moved, exposed to temperature swings, drought stress, or low humidity. Avoid repositioning a flowering plant; maintain consistent temperature above 15°C and keep soil evenly moist during budding. A stable environment is key to seeing blooms to maturity.

What lady of the night's hardiness rating actually means

Lady 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 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 9-11 — 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). Lady of the Night has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Lady of the Night hardiness — frequently asked questions

Is lady of the night cold hardy?

Lady 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. Lady of the Night can only live outside year-round in genuinely frost-free climates (roughly USDA 9-11); everywhere else it is a houseplant that summers out at most.

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

What hardiness zone is lady of the night?

Lady of the Night is rated USDA 9-11 and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can lady of the night 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 lady of the night 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.