Cold hardiness & minimum temperature

Is Calamondin orange (Citrus × microcarpa)cold hardy? Hardiness zone & min temp

Also called Panama orange, calamansi, calamondin, Philippine lime, × Citrofortunella microcarpa, miniature orange.

More about calamondin orange

About Calamondin orange

Citrus × microcarpa · also called Panama orange, calamansi · edible

The calamondin (Citrus × microcarpa) is a compact ornamental citrus prized for fragrant blossom and tart, edible orange fruit. It needs bright light, warmth, citrus feed and even moisture. Per the ASPCA, all true citrus are toxic to cats, dogs and horses: leaves, peel and oils cause vomiting, diarrhoea and dermatitis, though the ripe fruit flesh is edible.

Cold limit: USDA USDA zones 8b–11 (one of the hardiest citrus, but treat as frost-tender; protect below about 4°C / 40°F) · RHS RHS H3 (hardy only in mild coastal or city areas; needs a frost-free conservatory or indoors over winter in most of the UK) (16-27°C)

Watch for — Leaf drop: Usually caused by sudden temperature swings, cold draughts, over- or under-watering, or a sharp move from outdoors to a dry heated room.

What calamondin orange's hardiness rating actually means

Calamondin orange is half-hardy (RHS H3). It survives a mild winter outdoors in a sheltered spot, but a hard frost kills it — so in colder zones it is lifted, potted, or grown as a tender plant. Its RHS rating of H3 means: Half-hardy — comes through mild UK winters outside but is killed by a hard freeze. On the US scale that maps to USDA USDA zones 8b–11 (one of the hardiest citrus, but treat as frost-tender; protect below about 4°C / 40°F) — 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 to 1 °C — a light, short frost only. Calamondin orange shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for calamondin orange as it gets too cold:

Down to roughly about −5 to 1 °C it copes, especially if dry and sheltered.
A sustained hard frost collapses the top growth; whether it returns depends on whether the roots, crown or tubers froze.
Wet cold is far more lethal than dry cold for this plant — soggy, frozen soil is the usual killer.

Can calamondin orange go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA USDA zones 8b–11 (one of the hardiest citrus, but treat as frost-tender; protect below about 4°C / 40°F) or a frost-free UK microclimate.
In colder zones, grow it in a pot you can move under cover, or lift its tubers/roots and store them frost-free over winter.
A south-facing wall, free-draining soil and a dry winter position can push it a full zone hardier than the books suggest.

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 calamondin orange can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H3 figure above.

Frost protection for borderline calamondin orange

Calamondin orange is right on a hardiness edge in many gardens, so if you are pushing it, these measures buy it the margin it needs:

Mulch the crown or root zone deeply with bark, straw or leaf-mould before the first hard frost.
Move container plants against a warm wall or into an unheated but frost-free porch or greenhouse.
Fleece the top growth on the coldest nights, and keep it on the dry side — dry roots survive cold far better than wet ones.
Lift dahlia-type tubers or tender crowns after the first light frost blackens the foliage and store them somewhere cool but frost-free.

Calamondin orange hardiness — frequently asked questions

Is calamondin orange cold hardy?

Calamondin orange is half-hardy (RHS H3). It survives a mild winter outdoors in a sheltered spot, but a hard frost kills it — so in colder zones it is lifted, potted, or grown as a tender plant. Borderline outdoors. In its mild end of USDA USDA zones 8b–11 (one of the hardiest citrus, but treat as frost-tender; protect below about 4°C / 40°F) (and sheltered UK gardens) calamondin orange can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature calamondin orange can survive?

Minimum survivable temperature is roughly about −5 to 1 °C — a light, short frost only. Calamondin orange shrugs off cold nights but a real, sustained freeze will kill it.

What hardiness zone is calamondin orange?

Calamondin orange is rated USDA USDA zones 8b–11 (one of the hardiest citrus, but treat as frost-tender; protect below about 4°C / 40°F) and RHS H3 — Half-hardy — comes through mild UK winters outside but is killed by a hard freeze.

Can calamondin orange survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA USDA zones 8b–11 (one of the hardiest citrus, but treat as frost-tender; protect below about 4°C / 40°F) or a frost-free UK microclimate. In colder zones, grow it in a pot you can move under cover, or lift its tubers/roots and store them frost-free over winter. A south-facing wall, free-draining soil and a dry winter position can push it a full zone hardier than the books suggest.

How do I protect calamondin orange from frost?

Mulch the crown or root zone deeply with bark, straw or leaf-mould before the first hard frost. Move container plants against a warm wall or into an unheated but frost-free porch or greenhouse. Fleece the top growth on the coldest nights, and keep it on the dry side — dry roots survive cold far better than wet ones. Lift dahlia-type tubers or tender crowns after the first light frost blackens the foliage and store them somewhere cool but frost-free.