Cold hardiness & minimum temperature

Is Poinsettia (Euphorbia pulcherrima)cold hardy? Hardiness zone & min temp

Also called Poinsettia, Christmas star, Christmas flower, Mexican flame leaf, Painted leaf, Lobster flower.

More about poinsettia

About Poinsettia

Euphorbia pulcherrima · also called Poinsettia, Christmas star · flowering

Poinsettia is the iconic red-and-green Christmas houseplant, prized for its colourful bracts (not true flowers). It wants bright indirect light, warmth around 18-21C, and careful watering. It is mildly toxic to cats and dogs — the ASPCA lists it as toxic, but its danger is widely overstated and serious poisoning is very rare.

Cold limit: USDA 9-11 (grown as a tender houseplant elsewhere) (18-21C day, 13-18C night)

Watch for — Leaf and bract drop: Usually caused by cold drafts, chilly windows, sudden temperature swings, or the cold trip home from the shop. Keep away from doors, heat vents, and fireplaces, and maintain steady warmth above 13C (55F).

What poinsettia's hardiness rating actually means

Poinsettia is half-hardy (RHS H2). 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 H2 means: Tender — survives a frost-free greenhouse or a very mild, sheltered spot. On the US scale that maps to USDA 9-11 (grown as a tender houseplant 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 1 to 5 °C — tolerates cold but no real frost. Poinsettia shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for poinsettia as it gets too cold:

Down to roughly about 1 to 5 °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 poinsettia go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-11 (grown as a tender houseplant elsewhere) 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 poinsettia can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H2 figure above.

Frost protection for borderline poinsettia

Poinsettia 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.

Poinsettia hardiness — frequently asked questions

Is poinsettia cold hardy?

Poinsettia is half-hardy (RHS H2). 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 9-11 (grown as a tender houseplant elsewhere) (and sheltered UK gardens) poinsettia can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature poinsettia can survive?

Minimum survivable temperature is roughly about 1 to 5 °C — tolerates cold but no real frost. Poinsettia shrugs off cold nights but a real, sustained freeze will kill it.

What hardiness zone is poinsettia?

Poinsettia is rated USDA 9-11 (grown as a tender houseplant elsewhere) and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can poinsettia survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-11 (grown as a tender houseplant elsewhere) 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 poinsettia 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.