Cold hardiness & minimum temperature

Is Mandaianum Blue Star Fern (Phlebodium aureum 'Mandaianum')cold hardy? Hardiness zone & min temp

Also called Crisped blue star fern, Lettuce fern.

More about mandaianum blue star fern

About Mandaianum Blue Star Fern

Phlebodium aureum 'Mandaianum' · also called Crisped blue star fern, Lettuce fern · houseplant

'Mandaianum' is a distinctive blue star fern selection with wavy, ruffled and crested frond margins that give it a lettuce-like, frilly look. Like all Phlebodium aureum it is an easy-going epiphytic fern with bluish fronds and a furry creeping rhizome, tolerating average humidity and occasional dryness far better than typical ferns.

Cold limit: USDA 9-11 (indoor in most US and UK homes) · RHS H1b (16-24°C)

What mandaianum blue star fern's hardiness rating actually means

Mandaianum Blue Star 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 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 9-11 (indoor in most US and UK homes) — 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). Mandaianum Blue Star Fern has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for mandaianum blue star fern as it gets too cold:

Below about about 10 °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 mandaianum blue star fern go outside or overwinter — and where?

It can holiday outdoors in summer once nights are reliably above 10 °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 mandaianum blue star fern can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1b figure above.

Mandaianum Blue Star Fern hardiness — frequently asked questions

Is mandaianum blue star fern cold hardy?

Mandaianum Blue Star 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. Mandaianum Blue Star Fern can only live outside year-round in genuinely frost-free climates (roughly USDA 9-11 (indoor in most US and UK homes)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature mandaianum blue star fern can survive?

What hardiness zone is mandaianum blue star fern?

Mandaianum Blue Star Fern is rated USDA 9-11 (indoor in most US and UK homes) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can mandaianum blue star fern survive winter outside?

It can holiday outdoors in summer once nights are reliably above 10 °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 mandaianum blue star fern below its minimum temperature?

Below about about 10 °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.