Cold hardiness & minimum temperature

Is Nihoa Palm (Pritchardia remota)cold hardy? Hardiness zone & min temp

Also called Nihoa Palm, Nihoa Loulu.

More about nihoa palm

About Nihoa Palm

Pritchardia remota · also called Nihoa Palm, Nihoa Loulu · tropical

Pritchardia remota is a critically endangered fan palm endemic to the remote, uninhabited island of Nihoa in the Northwestern Hawaiian Islands. One of the rarest palms in the world, surviving in extremely harsh, arid, wind-swept conditions. Rarely cultivated outside specialist conservation collections. True palms are generally pet-safe.

Cold limit: USDA 10-12 · RHS H2 (15-32°C)

What nihoa palm's hardiness rating actually means

Nihoa Palm 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 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 1 to 5 °C — tolerates cold but no real frost. Nihoa Palm shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for nihoa palm 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 nihoa palm go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 10-12 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 nihoa palm 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 nihoa palm

Nihoa Palm 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.

Nihoa Palm hardiness — frequently asked questions

Is nihoa palm cold hardy?

Nihoa Palm 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 10-12 (and sheltered UK gardens) nihoa palm can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature nihoa palm can survive?

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

What hardiness zone is nihoa palm?

Nihoa Palm is rated USDA 10-12 and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can nihoa palm survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 10-12 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 nihoa palm 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.