Cold hardiness & minimum temperature

Is Longan (Nephelium longana)cold hardy? Hardiness zone & min temp

Also called Longan, Dragon's Eye, Dimocarpus longan.

More about longan

About Longan

Nephelium longana · also called Longan, Dragon's Eye · tropical

Longan is a fast-growing subtropical to tropical fruit tree in the Sapindaceae family, prized for translucent, sweet arils. It is self-fertile, begins fruiting relatively early, and tolerates brief mild cold spells better than its close relative lychee. Best grown outdoors in frost-free climates; thrives in full sun with well-draining slightly acidic soil.

Cold limit: USDA 9b–11 · RHS H1b (15–35°C)

Watch for — Failure to flower: Longan requires a cool, dry rest period in autumn/winter (temperatures around 15°C / 59°F for 4–6 weeks) to reliably set flower buds. Trees kept too warm year-round often produce vegetative growth only.

What longan's hardiness rating actually means

Longan 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 9b–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). Longan has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Longan hardiness — frequently asked questions

Is longan cold hardy?

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

What is the minimum temperature longan can survive?

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

What hardiness zone is longan?

Longan is rated USDA 9b–11 and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can longan 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 longan 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.