Cold hardiness & minimum temperature

Is Butterfield Holly Fern (Cyrtomium falcatum 'Butterfieldii')cold hardy? Hardiness zone & min temp

Also called Butterfield Holly Fern, Japanese Holly Fern.

More about butterfield holly fern

About Butterfield Holly Fern

Cyrtomium falcatum 'Butterfieldii' · also called Butterfield Holly Fern, Japanese Holly Fern · houseplant

A robust, glossy-leaved holly fern cultivar with broad, sickle-shaped pinnae that give it a bold, architectural look. Unusually drought- and pollution-tolerant for a fern, it adapts well to typical indoor conditions. The 'Butterfieldii' form is more compact than the species and sports particularly lustrous, dark green fronds year-round.

Cold limit: USDA 6–10 · RHS H4 (7–24°C)

What butterfield holly fern's hardiness rating actually means

Yes — butterfield holly fern is genuinely cold hardy. Rated RHS H4 and USDA 6–10, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H4 means: Hardy in an average winter across much of the temperate world. On the US scale that maps to USDA 6–10 — 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 −10 to −5 °C. Butterfield Holly Fern is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for butterfield holly fern as it gets too cold:

It tolerates winter lows to about −10 to −5 °C once established.
Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root.
First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.

Can butterfield holly fern go outside or overwinter — and where?

Plant it out within USDA 6–10 and it overwinters with little or no help.
It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy.
The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

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 butterfield holly fern can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H4 figure above.

Butterfield Holly Fern hardiness — frequently asked questions

Is butterfield holly fern cold hardy?

Yes — butterfield holly fern is genuinely cold hardy. Rated RHS H4 and USDA 6–10, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Butterfield Holly Fern is hardy across USDA 6–10; it belongs in the ground or a frost-proof container, not on a windowsill, and many types actively need a cold winter to perform.

What is the minimum temperature butterfield holly fern can survive?

Minimum survivable temperature is roughly about −10 to −5 °C. Butterfield Holly Fern is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is butterfield holly fern?

Butterfield Holly Fern is rated USDA 6–10 and RHS H4 — Hardy in an average winter across much of the temperate world.

Can butterfield holly fern survive winter outside?

Plant it out within USDA 6–10 and it overwinters with little or no help. It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy. The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

What happens to butterfield holly fern below its minimum temperature?

It tolerates winter lows to about −10 to −5 °C once established. Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root. First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.