Cold hardiness & minimum temperature

Is Citron (Citrus medica)cold hardy? Hardiness zone & min temp

Also called Citron, Buddha's hand, Corsican citron, Etrog.

More about citron

About Citron

Citrus medica · also called Citron, Buddha's hand · edible

Citron is one of the original three ancestral Citrus species, grown for its enormous, fragrant, thick-rinded fruit rather than juice. The Buddha's hand form (var. sarcodactylis) is fingered and entirely pith with no pulp. Used for candied peel, liqueurs, perfumery, and religious ritual. Tender and best grown in sheltered warm conditions or large containers.

Cold limit: USDA 10-12 · RHS H1b (12-35°C)

Watch for — Cold and wind damage: Citron is the most frost-tender major citrus. Even cool temperatures below 10°C slow growth noticeably. In the UK, it must be overwintered frost-free and sheltered from cold drying winds year-round.

What citron's hardiness rating actually means

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

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

Citron hardiness — frequently asked questions

Is citron cold hardy?

Citron 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. Citron can only live outside year-round in genuinely frost-free climates (roughly USDA 10-12); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature citron can survive?

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

What hardiness zone is citron?

Citron is rated USDA 10-12 and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can citron 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 citron 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.