Cold hardiness & minimum temperature

Is Lucky Nut (Cascabela thevetia)cold hardy? Hardiness zone & min temp

Also called Lucky Nut, Be-Still Tree, Yellow Oleander, Cascabela.

More about lucky nut

About Lucky Nut

Cascabela thevetia · also called Lucky Nut, Be-Still Tree · tropical

Lucky Nut is an evergreen tropical shrub or small tree widely grown for its cheerful yellow (or apricot-flushed) funnel-shaped flowers and hard, nut-like fruits that have been used as charms in some cultures. It adapts readily to various soil types, is drought-tolerant once established, and blooms prolifically in full sun. The accepted current name for this species; all parts are deadly toxic due to cardiac glycosides.

Cold limit: USDA 8a–10b · RHS H1b (2–38°C; frost-tender; tolerates brief dips to about -2°C if dry)

Watch for — Frost damage in marginal zones: Temperatures below 0°C (32°F) blacken foliage and kill stems. In USDA Zone 8, grow in containers and bring under cover in winter, or plant against a south-facing wall with heavy mulch. The plant often regenerates from the root crown after a light frost.

What lucky nut's hardiness rating actually means

Lucky Nut 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 8a–10b — 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). Lucky Nut has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Lucky Nut hardiness — frequently asked questions

Is lucky nut cold hardy?

Lucky Nut 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. Lucky Nut can only live outside year-round in genuinely frost-free climates (roughly USDA 8a–10b); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature lucky nut can survive?

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

What hardiness zone is lucky nut?

Lucky Nut is rated USDA 8a–10b and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can lucky nut 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 lucky nut 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.