Cold hardiness & minimum temperature

Is Roosevelt Fern (Nephrolepis exaltata 'Rooseveltii')cold hardy? Hardiness zone & min temp

Also called Roosevelt Fern, Feather Fern, Crested Boston Fern.

More about roosevelt fern

About Roosevelt Fern

Nephrolepis exaltata 'Rooseveltii' · also called Roosevelt Fern, Feather Fern · houseplant

A cultivar of the Boston fern prized for its finely cut, feathery fronds with crested, ruffled tips. It thrives in bright indirect light and consistently moist soil, demanding high humidity to prevent brown frond tips. Excellent as a hanging basket plant or for a humid bathroom shelf, rewarding steady moisture with lush, arching growth.

Cold limit: USDA 10–12 · RHS H1a (16–24°C)

What roosevelt fern's hardiness rating actually means

Roosevelt Fern is not cold hardy. It is a tropical houseplant that dies if it is left out through frost — there is no zone where it overwinters outdoors in a UK or cold-US climate. Its RHS rating of H1a means: Tropical — needs a heated room or greenhouse; no frost tolerance whatsoever. 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 above about 15 °C (warm, never cold). Roosevelt Fern has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for roosevelt fern as it gets too cold:

Below about above about 15 °C, growth stalls and the leaves start to show cold stress — dark, water-soaked, or yellowing patches.
A single light frost blackens the foliage; a hard freeze kills the whole plant, roots included, and it does not recover.
Even a cold, draughty windowsill or an unheated porch in winter can be enough to damage it permanently.

Can roosevelt fern go outside or overwinter — and where?

It can holiday outdoors in summer once nights are reliably above above 15 °C, in shade or dappled light, hardened off gradually.
Bring it back indoors well before the first autumn frost — do not wait for a frost warning, move it when nights drop toward 10-12 °C.
It will never overwinter outside in a temperate climate; the indoors is its winter home, full stop.

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 roosevelt fern can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1a figure above.

Roosevelt Fern hardiness — frequently asked questions

Is roosevelt fern cold hardy?

Roosevelt Fern is not cold hardy. It is a tropical houseplant that dies if it is left out through frost — there is no zone where it overwinters outdoors in a UK or cold-US climate. Indoor-only in almost every home. Roosevelt Fern can only live outside year-round in genuinely frost-free climates (roughly USDA 10–12); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature roosevelt fern can survive?

Minimum survivable temperature is roughly above about 15 °C (warm, never cold). Roosevelt Fern has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

What hardiness zone is roosevelt fern?

Roosevelt Fern is rated USDA 10–12 and RHS H1a — Tropical — needs a heated room or greenhouse; no frost tolerance whatsoever.

Can roosevelt fern survive winter outside?

It can holiday outdoors in summer once nights are reliably above above 15 °C, in shade or dappled light, hardened off gradually. Bring it back indoors well before the first autumn frost — do not wait for a frost warning, move it when nights drop toward 10-12 °C. It will never overwinter outside in a temperate climate; the indoors is its winter home, full stop.

What happens to roosevelt fern below its minimum temperature?

Below about above about 15 °C, growth stalls and the leaves start to show cold stress — dark, water-soaked, or yellowing patches. A single light frost blackens the foliage; a hard freeze kills the whole plant, roots included, and it does not recover. Even a cold, draughty windowsill or an unheated porch in winter can be enough to damage it permanently.