Cold hardiness & minimum temperature

Is Green Spleenwort (Asplenium viride)cold hardy? Hardiness zone & min temp

Also called Green Spleenwort, Green Maidenhair Spleenwort.

More about green spleenwort

About Green Spleenwort

Asplenium viride · also called Green Spleenwort, Green Maidenhair Spleenwort · houseplant

Green Spleenwort is a delicate, lime-loving fern native to calcareous rock crevices across alpine and subalpine regions of Europe, North America, and Asia. It thrives in cool, shaded positions with consistently moist, well-drained, alkaline soil — unlike most ferns it actively requires calcium-rich substrate. The single most important care fact is that it must never be planted in acidic compost; always incorporate limestone grit or crushed oyster shell into the growing medium. Asplenium viride is not listed as toxic by the ASPCA; it is considered pet-safe.

Cold limit: USDA 4-8 · RHS H7 (-20 to 20 °C)

What green spleenwort's hardiness rating actually means

Yes — green spleenwort is genuinely cold hardy. Rated RHS H7 and USDA 4-8, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H7 means: Hardy in the severest European continental winters. On the US scale that maps to USDA 4-8 — 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 below about −20 °C. Green Spleenwort is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for green spleenwort as it gets too cold:

It tolerates winter lows to about −20 °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 green spleenwort go outside or overwinter — and where?

Plant it out within USDA 4-8 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 green spleenwort can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Green Spleenwort hardiness — frequently asked questions

Is green spleenwort cold hardy?

Yes — green spleenwort is genuinely cold hardy. Rated RHS H7 and USDA 4-8, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Green Spleenwort is hardy across USDA 4-8; 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 green spleenwort can survive?

Minimum survivable temperature is roughly below about −20 °C. Green Spleenwort is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is green spleenwort?

Green Spleenwort is rated USDA 4-8 and RHS H7 — Hardy in the severest European continental winters.

Can green spleenwort survive winter outside?

Plant it out within USDA 4-8 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 green spleenwort below its minimum temperature?

It tolerates winter lows to about −20 °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.