Cold hardiness & minimum temperature

Is Erect Moss Fern (Selaginella erythropus)cold hardy? Hardiness zone & min temp

Also called Red Selaginella, Ruby Spikemoss, Erect Spikemoss.

More about erect moss fern

About Erect Moss Fern

Selaginella erythropus · also called Red Selaginella, Ruby Spikemoss · houseplant

Selaginella erythropus is a striking spikemoss from tropical America with reddish-tinged undersides on its branching fronds. It forms neat, upright clumps ideal for terrariums and humid displays. Like most Selaginella, it carries no known toxicity and is not listed as harmful by the ASPCA.

Cold limit: USDA 11-12 (indoor-only in most climates) · RHS H1c (16-27°C)

What erect moss fern's hardiness rating actually means

Erect Moss 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 11-12 (indoor-only 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 about 5 °C (and never frost). Erect Moss Fern has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for erect moss 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 erect moss 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 erect moss fern can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c figure above.

Erect Moss Fern hardiness — frequently asked questions

Is erect moss fern cold hardy?

Erect Moss 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. Erect Moss Fern can only live outside year-round in genuinely frost-free climates (roughly USDA 11-12 (indoor-only in most climates)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature erect moss fern can survive?

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

What hardiness zone is erect moss fern?

Erect Moss Fern is rated USDA 11-12 (indoor-only in most climates) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can erect moss 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 erect moss 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.