Cold hardiness & minimum temperature

Is Ring Fern (Paesia scaberula)cold hardy? Hardiness zone & min temp

Also called Ring Fern, Scented Fern, Lace Fern, Scented Lace Fern.

More about ring fern

About Ring Fern

Paesia scaberula · also called Ring Fern, Scented Fern · houseplant

Paesia scaberula is a fast-growing, deciduous, rhizomatous fern native to New Zealand, where it colonises open, dry, rocky cliff faces and disturbed ground. It produces elegantly lacy, finely divided fronds up to 1 m tall on dark, rough stalks, and releases a pleasant aromatic scent when the foliage is crushed or wetted by rain. The key care fact is that it tolerates drier, sunnier conditions than most ferns, spreading energetically by long-creeping rhizomes that require containment in smaller gardens. Not listed in the ASPCA database; treat as mildly-toxic to pets as a precaution.

Cold limit: USDA 8-10 · RHS H3 (-5 to 28°C)

Watch for — Frost dieback in borderline zones: In USDA zone 8 or at the margins of RHS H3, fronds die back after hard frost but rhizomes typically survive; apply a 10 cm mulch of shredded bark or dry bracken over the crown in late autumn to protect the rhizomes and encourage faster spring regrowth.

What ring fern's hardiness rating actually means

Ring Fern is half-hardy (RHS H3). It survives a mild winter outdoors in a sheltered spot, but a hard frost kills it — so in colder zones it is lifted, potted, or grown as a tender plant. Its RHS rating of H3 means: Half-hardy — comes through mild UK winters outside but is killed by a hard freeze. On the US scale that maps to USDA 8-10 — 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 to 1 °C — a light, short frost only. Ring Fern shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for ring fern as it gets too cold:

Down to roughly about −5 to 1 °C it copes, especially if dry and sheltered.
A sustained hard frost collapses the top growth; whether it returns depends on whether the roots, crown or tubers froze.
Wet cold is far more lethal than dry cold for this plant — soggy, frozen soil is the usual killer.

Can ring fern go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 8-10 or a frost-free UK microclimate.
In colder zones, grow it in a pot you can move under cover, or lift its tubers/roots and store them frost-free over winter.
A south-facing wall, free-draining soil and a dry winter position can push it a full zone hardier than the books suggest.

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 ring fern can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H3 figure above.

Frost protection for borderline ring fern

Ring Fern is right on a hardiness edge in many gardens, so if you are pushing it, these measures buy it the margin it needs:

Mulch the crown or root zone deeply with bark, straw or leaf-mould before the first hard frost.
Move container plants against a warm wall or into an unheated but frost-free porch or greenhouse.
Fleece the top growth on the coldest nights, and keep it on the dry side — dry roots survive cold far better than wet ones.
Lift dahlia-type tubers or tender crowns after the first light frost blackens the foliage and store them somewhere cool but frost-free.

Ring Fern hardiness — frequently asked questions

Is ring fern cold hardy?

Ring Fern is half-hardy (RHS H3). It survives a mild winter outdoors in a sheltered spot, but a hard frost kills it — so in colder zones it is lifted, potted, or grown as a tender plant. Borderline outdoors. In its mild end of USDA 8-10 (and sheltered UK gardens) ring fern can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature ring fern can survive?

Minimum survivable temperature is roughly about −5 to 1 °C — a light, short frost only. Ring Fern shrugs off cold nights but a real, sustained freeze will kill it.

What hardiness zone is ring fern?

Ring Fern is rated USDA 8-10 and RHS H3 — Half-hardy — comes through mild UK winters outside but is killed by a hard freeze.

Can ring fern survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 8-10 or a frost-free UK microclimate. In colder zones, grow it in a pot you can move under cover, or lift its tubers/roots and store them frost-free over winter. A south-facing wall, free-draining soil and a dry winter position can push it a full zone hardier than the books suggest.

How do I protect ring fern from frost?

Mulch the crown or root zone deeply with bark, straw or leaf-mould before the first hard frost. Move container plants against a warm wall or into an unheated but frost-free porch or greenhouse. Fleece the top growth on the coldest nights, and keep it on the dry side — dry roots survive cold far better than wet ones. Lift dahlia-type tubers or tender crowns after the first light frost blackens the foliage and store them somewhere cool but frost-free.