Cold hardiness & minimum temperature

Is Fortune's Holly Fern (Cyrtomium fortunei)cold hardy? Hardiness zone & min temp

Also called Fortune's Holly Fern, Japanese Holly Fern.

More about fortune's holly fern

About Fortune's Holly Fern

Cyrtomium fortunei · also called Fortune's Holly Fern, Japanese Holly Fern · flowering

Cyrtomium fortunei is a tough, semi-evergreen holly fern with matte, leathery, holly-like pinnae on arching fronds. Hardier and more cold-tolerant than its glossy cousin C. falcatum, it suits shady borders, courtyards and cool rooms. Forgiving of dry spells and lower light, it forms a neat, architectural rosette and reliably handles temperate winters.

Cold limit: USDA 6-10 · RHS H5 (5-24°C)

Watch for — Crown rot in wet winters: Soggy, poorly drained soil rots the crown. Improve drainage and ease off watering through cold months.

What fortune's holly fern's hardiness rating actually means

Yes — fortune's holly fern is genuinely cold hardy. Rated RHS H5 and USDA 6-10, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H5 means: Hardy in most of the UK and in cold winters. 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 −15 to −10 °C. Fortune's Holly Fern is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for fortune's holly fern as it gets too cold:

It tolerates winter lows to about −15 to −10 °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 fortune's 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 fortune's holly fern can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Fortune's Holly Fern hardiness — frequently asked questions

Is fortune's holly fern cold hardy?

Yes — fortune's holly fern is genuinely cold hardy. Rated RHS H5 and USDA 6-10, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Fortune's 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 fortune's holly fern can survive?

Minimum survivable temperature is roughly about −15 to −10 °C. Fortune's Holly Fern is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is fortune's holly fern?

Fortune's Holly Fern is rated USDA 6-10 and RHS H5 — Hardy in most of the UK and in cold winters.

Can fortune's 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 fortune's holly fern below its minimum temperature?

It tolerates winter lows to about −15 to −10 °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.