Cold hardiness & minimum temperature

Is Woolly Lip Fern (Cheilanthes newberryi)cold hardy? Hardiness zone & min temp

Also called Newberry's Lip Fern, Woolly Lace Fern.

More about woolly lip fern

About Woolly Lip Fern

Cheilanthes newberryi · also called Newberry's Lip Fern, Woolly Lace Fern · houseplant

Woolly Lip Fern is a compact, drought-adapted fern from rocky desert slopes of the American Southwest, distinguished by the dense white wool (tomentum) that covers the frond undersides and stems. This coating reduces water loss, enabling exceptional drought tolerance. True ferns in the Pteridaceae family are generally considered non-toxic to pets.

Cold limit: USDA 7-10 · RHS H3 (5-32°C)

What woolly lip fern's hardiness rating actually means

Woolly Lip 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 7-10 — 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. Woolly Lip Fern shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for woolly lip 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 woolly lip fern go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 7-10 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 woolly lip 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 woolly lip fern

Woolly Lip 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.

Woolly Lip Fern hardiness — frequently asked questions

Is woolly lip fern cold hardy?

Woolly Lip 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 7-10 (and sheltered UK gardens) woolly lip 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 woolly lip fern can survive?

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

What hardiness zone is woolly lip fern?

Woolly Lip Fern is rated USDA 7-10 and RHS H3 — Half-hardy — comes through mild UK winters outside but is killed by a hard freeze.

Can woolly lip fern survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 7-10 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 woolly lip 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.