Cold hardiness & minimum temperature

Is Crested Hart's Tongue Fern (Asplenium scolopendrium 'Crispum')cold hardy? Hardiness zone & min temp

Also called Crested Hart's Tongue Fern, Crispum Hart's Tongue Fern, Hart's Tongue Fern.

More about crested hart's tongue fern

About Crested Hart's Tongue Fern

Asplenium scolopendrium 'Crispum' · also called Crested Hart's Tongue Fern, Crispum Hart's Tongue Fern · houseplant

A garden cultivar of the native European hart's tongue fern, grown for its distinctive strap-shaped, glossy evergreen fronds with attractively ruffled and crisped margins. It thrives in cool, moist, partially shaded spots in humus-rich, slightly alkaline to neutral, well-drained soil — limestone-derived soils are ideal. The most critical care point is ensuring consistent moisture without waterlogging, as both drought and soggy roots cause frond scorch and rot respectively. Asplenium scolopendrium is widely regarded as non-toxic to cats and dogs.

Cold limit: USDA 5-8 · RHS H6 (-15°C to 20°C)

Watch for — Root rot / crown rot: Caused by waterlogged soil, especially in winter; ensure free drainage and avoid mulching directly over the crown — keep the rhizome at or just above soil level.

What crested hart's tongue fern's hardiness rating actually means

Yes — crested hart's tongue fern is genuinely cold hardy. Rated RHS H6 and USDA 5-8, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H6 means: Hardy throughout the UK and northern Europe. On the US scale that maps to USDA 5-8 — 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 −20 to −15 °C. Crested Hart's Tongue Fern is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for crested hart's tongue fern as it gets too cold:

It tolerates winter lows to about −20 to −15 °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 crested hart's tongue fern go outside or overwinter — and where?

Plant it out within USDA 5-8 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 crested hart's tongue fern can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Crested Hart's Tongue Fern hardiness — frequently asked questions

Is crested hart's tongue fern cold hardy?

Yes — crested hart's tongue fern is genuinely cold hardy. Rated RHS H6 and USDA 5-8, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Crested Hart's Tongue Fern is hardy across USDA 5-8; 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 crested hart's tongue fern can survive?

Minimum survivable temperature is roughly about −20 to −15 °C. Crested Hart's Tongue Fern is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is crested hart's tongue fern?

Crested Hart's Tongue Fern is rated USDA 5-8 and RHS H6 — Hardy throughout the UK and northern Europe.

Can crested hart's tongue fern survive winter outside?

Plant it out within USDA 5-8 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 crested hart's tongue fern below its minimum temperature?

It tolerates winter lows to about −20 to −15 °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.