Cold hardiness & minimum temperature

Is Rocky Mountain Woodsia (Woodsia scopulina)cold hardy? Hardiness zone & min temp

Also called Rocky Mountain Woodsia, Rocky Mountain Cliff Fern.

More about rocky mountain woodsia

About Rocky Mountain Woodsia

Woodsia scopulina · also called Rocky Mountain Woodsia, Rocky Mountain Cliff Fern · houseplant

Woodsia scopulina is a small deciduous fern native to rocky cliffs and talus slopes across western North America, from Alaska south to Arizona and California. It thrives in cool, shaded, north- or east-facing rock crevices in well-drained, gritty soil and performs poorly in heavy clay or consistently wet conditions. The single most important care fact is that it requires excellent drainage and resents wet roots — plant it in a gritty, free-draining mix and never allow water to pool. It is not listed as toxic to cats or dogs by the ASPCA.

Cold limit: USDA 3-8 · RHS H7 (-20°C to 25°C)

What rocky mountain woodsia's hardiness rating actually means

Yes — rocky mountain woodsia is genuinely cold hardy. Rated RHS H7 and USDA 3-8, 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 3-8 — 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. Rocky Mountain Woodsia is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for rocky mountain woodsia 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 rocky mountain woodsia go outside or overwinter — and where?

Plant it out within USDA 3-8 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 rocky mountain woodsia can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Rocky Mountain Woodsia hardiness — frequently asked questions

Is rocky mountain woodsia cold hardy?

Yes — rocky mountain woodsia is genuinely cold hardy. Rated RHS H7 and USDA 3-8, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Rocky Mountain Woodsia is hardy across USDA 3-8; 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 rocky mountain woodsia can survive?

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

What hardiness zone is rocky mountain woodsia?

Rocky Mountain Woodsia is rated USDA 3-8 and RHS H7 — Hardy in the severest European continental winters.

Can rocky mountain woodsia survive winter outside?

Plant it out within USDA 3-8 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 rocky mountain woodsia 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.