Cold hardiness & minimum temperature

Is Fadang (Cycas micronesica)cold hardy? Hardiness zone & min temp

Also called Fadang, Guam Cycad, Micronesian Cycad.

More about fadang

About Fadang

Cycas micronesica · also called Fadang, Guam Cycad · tropical

Cycas micronesica — known locally as 'fadang' — is endemic to the islands of Guam, Palau, Yap, and Rota in Micronesia, where it was once extremely abundant in the limestone forest understorey but is now critically endangered due to the accidental introduction of cycad scale and the cycad aulacaspis scale. It is a medium-sized cycad with a slender trunk and graceful dark-green pinnate fronds. The most critical care requirement is vigilant monitoring for cycad scale, which can devastate this species rapidly. All parts are highly toxic to pets and humans.

Cold limit: USDA 10-12 (indoor in most climates) · RHS H1a (18–35°C)

Watch for — Crown rot in cool, wet conditions: Being a tropical island species, fadang is particularly vulnerable to fungal crown rot when kept below 18°C in wet conditions; the central growing point collapses. In the UK, overwinter under glass above 18°C and keep the crown dry; improve drainage and air circulation at all times.

What fadang's hardiness rating actually means

Fadang 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 (indoor in most climates) — 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). Fadang has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Fadang hardiness — frequently asked questions

Is fadang cold hardy?

Fadang 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. Fadang can only live outside year-round in genuinely frost-free climates (roughly USDA 10-12 (indoor in most climates)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature fadang can survive?

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

What hardiness zone is fadang?

Fadang is rated USDA 10-12 (indoor in most climates) and RHS H1a — Tropical — needs a heated room or greenhouse; no frost tolerance whatsoever.

Can fadang 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 fadang 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.