Cold hardiness & minimum temperature

Is Taxiphyllum alternans (Taxiphyllum alternans)cold hardy? Hardiness zone & min temp

Also called Taiwan moss, alternating moss.

More about taxiphyllum alternans

About Taxiphyllum alternans

Taxiphyllum alternans · also called Taiwan moss, alternating moss · tropical

Taxiphyllum alternans, Taiwan moss, is an Asian aquarium moss prized for the way its branching fronds drape in neat, slightly pendulous tiers. Grown fully submerged, it attaches to wood and rock to form an elegant, layered cascade. Slightly more particular than Java moss, it looks its best with good flow, moderate light and added CO2.

Cold limit: USDA Not applicable (indoor tropical aquarium plant) (20-28°C)

What taxiphyllum alternans's hardiness rating actually means

Taxiphyllum alternans 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 Not applicable (indoor tropical aquarium plant) — 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). Taxiphyllum alternans has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for taxiphyllum alternans 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 taxiphyllum alternans 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 taxiphyllum alternans can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1b figure above.

Taxiphyllum alternans hardiness — frequently asked questions

Is taxiphyllum alternans cold hardy?

Taxiphyllum alternans 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. Taxiphyllum alternans can only live outside year-round in genuinely frost-free climates (roughly USDA Not applicable (indoor tropical aquarium plant)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature taxiphyllum alternans can survive?

What hardiness zone is taxiphyllum alternans?

Taxiphyllum alternans is rated USDA Not applicable (indoor tropical aquarium plant) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can taxiphyllum alternans 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 taxiphyllum alternans 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.