Cold hardiness & minimum temperature

Is Navel orange (Citrus sinensis 'Navel')cold hardy? Hardiness zone & min temp

Also called Navel orange, Washington navel, Seedless orange.

More about navel orange

About Navel orange

Citrus sinensis 'Navel' · also called Navel orange, Washington navel · edible

Navel orange is a seedless, sweet dessert orange recognised by the small secondary fruit ('navel') at the blossom end. It ripens in winter–spring and is prized for fresh eating. Full sun, well-drained slightly acidic soil, and a long warm season are essential. Dwarf grafted forms suit containers and patios in cool climates.

Cold limit: USDA 9-10 · RHS H1b (15–30°C optimal; fruit damaged below -2°C)

Watch for — Navel end splitting / creasing: Fruit split at the navel end results from irregular watering or temperature fluctuations during fruit development. Maintain even soil moisture and protect from sudden cold snaps while fruit is swelling.

What navel orange's hardiness rating actually means

Navel orange is a tender fruiting plant, not a hardy one. It crops outdoors only in roughly USDA 9-10; in cooler zones it is a container plant moved under cover for winter. 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 9-10 — 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). Navel orange fruits in warmth and is set back or killed by frost.

Concretely, for navel orange as it gets too cold:

Below about 10 °C the foliage and any fruit are damaged; a hard frost can kill the whole plant.
A light frost typically scorches leaves and ruins the current crop even when the framework survives.
Roots in a container freeze far faster than roots in the ground, so potted specimens need earlier protection.

Can navel orange go outside or overwinter — and where?

It can stay outdoors year-round only in USDA 9-10; in a UK or cold-US climate it is a conservatory or move-it-indoors plant for winter.
Summer it outside in full sun for the best crop, then bring it into a cool, bright, frost-free room before the first frost.
A bright unheated (but frost-free) glasshouse or porch is the ideal overwintering spot — cool and dormant, never freezing.

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

Frost protection for borderline navel orange

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

Move containers into a frost-free glasshouse, porch or cool room before the first forecast frost.
For borderline-zone ground plants, wrap the trunk and fleece the canopy, and mulch the root zone heavily.
Keep it on the dry side over winter — cold plus wet roots is what actually kills tender fruit.

Navel orange hardiness — frequently asked questions

Is navel orange cold hardy?

Navel orange is a tender fruiting plant, not a hardy one. It crops outdoors only in roughly USDA 9-10; in cooler zones it is a container plant moved under cover for winter. Frost-tender. Grow navel orange in the ground only within USDA 9-10; everywhere colder it lives in a large pot that comes into a frost-free space each winter.

What is the minimum temperature navel orange can survive?

Minimum survivable temperature is roughly about 10 °C (sustained cold below this is damaging). Navel orange fruits in warmth and is set back or killed by frost.

What hardiness zone is navel orange?

Navel orange is rated USDA 9-10 and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can navel orange survive winter outside?

It can stay outdoors year-round only in USDA 9-10; in a UK or cold-US climate it is a conservatory or move-it-indoors plant for winter. Summer it outside in full sun for the best crop, then bring it into a cool, bright, frost-free room before the first frost. A bright unheated (but frost-free) glasshouse or porch is the ideal overwintering spot — cool and dormant, never freezing.

How do I protect navel orange from frost?

Move containers into a frost-free glasshouse, porch or cool room before the first forecast frost. For borderline-zone ground plants, wrap the trunk and fleece the canopy, and mulch the root zone heavily. Keep it on the dry side over winter — cold plus wet roots is what actually kills tender fruit.