Cold hardiness & minimum temperature

Is Green Cliff Brake Fern (Pellaea viridis)cold hardy? Hardiness zone & min temp

Also called Green Cliff Brake, Green Brake Fern.

More about green cliff brake fern

About Green Cliff Brake Fern

Pellaea viridis · also called Green Cliff Brake, Green Brake Fern · houseplant

Green Cliff Brake is a small, neat fern from southern Africa with bright green, pinnate fronds on dark, wiry stems. It tolerates drier air and less frequent watering than most ferns, making it well suited to indoor cultivation. Not listed as toxic by the ASPCA; true ferns in the Pteridaceae family are generally considered pet-safe.

Cold limit: USDA 9-11 · RHS H2 (10-24°C)

What green cliff brake fern's hardiness rating actually means

Green Cliff Brake Fern is half-hardy (RHS H2). 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 H2 means: Tender — survives a frost-free greenhouse or a very mild, sheltered spot. On the US scale that maps to USDA 9-11 — 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 1 to 5 °C — tolerates cold but no real frost. Green Cliff Brake Fern shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for green cliff brake fern as it gets too cold:

Down to roughly about 1 to 5 °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 green cliff brake fern go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-11 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 green cliff brake fern can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H2 figure above.

Frost protection for borderline green cliff brake fern

Green Cliff Brake 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.

Green Cliff Brake Fern hardiness — frequently asked questions

Is green cliff brake fern cold hardy?

Green Cliff Brake Fern is half-hardy (RHS H2). 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 9-11 (and sheltered UK gardens) green cliff brake 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 green cliff brake fern can survive?

Minimum survivable temperature is roughly about 1 to 5 °C — tolerates cold but no real frost. Green Cliff Brake Fern shrugs off cold nights but a real, sustained freeze will kill it.

What hardiness zone is green cliff brake fern?

Green Cliff Brake Fern is rated USDA 9-11 and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can green cliff brake fern survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-11 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 green cliff brake 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.