Cold hardiness & minimum temperature

Is Lime Tree (Citrus × aurantiifolia)cold hardy? Hardiness zone & min temp

Also called key lime, Mexican lime.

More about lime tree

About Lime Tree

Citrus × aurantiifolia · also called key lime, Mexican lime · edible

The key (Mexican) lime is a small, thorny, frost-tender citrus bearing aromatic, highly acidic green-to-yellow fruit famous in cooking and drinks. The most cold-sensitive common citrus, it suits warm gardens and conservatory or container culture elsewhere. It flowers and fruits over a long season, demands full sun and sharp drainage, and rewards steady citrus feeding with heavy crops.

Cold limit: USDA 10-11 outdoors (the most frost-tender common citrus); container-grown and overwintered frost-free elsewhere · RHS H1b (15-32°C)

Watch for — Cold sensitivity: The least cold-hardy common citrus — damaged below about 4-7°C (40-45°F). Move containers indoors before first frost and protect from cold drafts; chilling causes leaf drop and dieback.

What lime tree's hardiness rating actually means

Lime Tree is a tender fruiting plant, not a hardy one. It crops outdoors only in roughly USDA 10-11 outdoors (the most frost-tender common citrus); container-grown and overwintered frost-free elsewhere; 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 10-11 outdoors (the most frost-tender common citrus); container-grown and overwintered frost-free elsewhere — 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). Lime Tree fruits in warmth and is set back or killed by frost.

Concretely, for lime tree 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 lime tree go outside or overwinter — and where?

It can stay outdoors year-round only in USDA 10-11 outdoors (the most frost-tender common citrus); container-grown and overwintered frost-free elsewhere; 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 lime tree 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 lime tree

Lime Tree 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.

Lime Tree hardiness — frequently asked questions

Is lime tree cold hardy?

Lime Tree is a tender fruiting plant, not a hardy one. It crops outdoors only in roughly USDA 10-11 outdoors (the most frost-tender common citrus); container-grown and overwintered frost-free elsewhere; in cooler zones it is a container plant moved under cover for winter. Frost-tender. Grow lime tree in the ground only within USDA 10-11 outdoors (the most frost-tender common citrus); container-grown and overwintered frost-free elsewhere; everywhere colder it lives in a large pot that comes into a frost-free space each winter.

What is the minimum temperature lime tree can survive?

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

What hardiness zone is lime tree?

Lime Tree is rated USDA 10-11 outdoors (the most frost-tender common citrus); container-grown and overwintered frost-free elsewhere and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can lime tree survive winter outside?

It can stay outdoors year-round only in USDA 10-11 outdoors (the most frost-tender common citrus); container-grown and overwintered frost-free elsewhere; 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 lime tree 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.