Cold hardiness & minimum temperature

Is Macho Fern (Nephrolepis biserrata 'Macho')cold hardy? Hardiness zone & min temp

Also called Giant sword fern, Broad sword fern.

More about macho fern

About Macho Fern

Nephrolepis biserrata 'Macho' · also called Giant sword fern, Broad sword fern · tropical

The Macho Fern is a large, robust sword fern with broad, arching fronds that can reach well over a metre long, giving a dramatic tropical presence on patios and in big rooms. It is more sun- and drought-tolerant than Boston ferns but still wants moisture and warmth, and it is fully pet-safe.

Cold limit: USDA 9-11 outdoors; container or houseplant elsewhere, bring in before frost · RHS H1c (16-27°C)

Watch for — Cold or frost damage: Fronds blacken below about 5°C. Bring containers indoors before frost; in borderline zones treat it as a tender summer plant or annual.

What macho fern's hardiness rating actually means

Macho 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 H1c means: Warm-temperate — can summer outdoors but must come in well before the first frost. On the US scale that maps to USDA 9-11 outdoors; container or houseplant elsewhere, bring in before frost — 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 5 °C (and never frost). Macho Fern has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for macho fern as it gets too cold:

Below about about 5 °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 macho fern go outside or overwinter — and where?

It can holiday outdoors in summer once nights are reliably above 5 °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 macho fern can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c figure above.

Macho Fern hardiness — frequently asked questions

Is macho fern cold hardy?

Macho 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. Macho Fern can only live outside year-round in genuinely frost-free climates (roughly USDA 9-11 outdoors; container or houseplant elsewhere, bring in before frost); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature macho fern can survive?

Minimum survivable temperature is roughly about 5 °C (and never frost). Macho Fern has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

What hardiness zone is macho fern?

Macho Fern is rated USDA 9-11 outdoors; container or houseplant elsewhere, bring in before frost and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can macho fern survive winter outside?

It can holiday outdoors in summer once nights are reliably above 5 °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 macho fern below its minimum temperature?

Below about about 5 °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.