Cold hardiness & minimum temperature

Is Polystichum setiferum 'Divisilobum' (Polystichum setiferum 'Divisilobum')cold hardy? Hardiness zone & min temp

Also called Divided Soft Shield Fern.

More about polystichum setiferum 'divisilobum'

About Polystichum setiferum 'Divisilobum'

Polystichum setiferum 'Divisilobum' · also called Divided Soft Shield Fern · flowering

Polystichum setiferum 'Divisilobum', the Divided Soft Shield Fern, is an elegant evergreen fern with finely divided, lacy fronds that arch outward in a soft, feathery rosette. Hardy and easy in moist, shady borders, it keeps its delicate foliage through winter and often produces plantlets along the frond midribs. A refined, low-maintenance choice for woodland and shade gardens.

Cold limit: USDA 5-8 (hardy evergreen fern) · RHS H5 (-12 to 24°C)

Watch for — Tatty old fronds in spring: Evergreen fronds look worn by late winter. Cut them back in early spring before the new croziers unfurl to keep the plant tidy.

What polystichum setiferum 'divisilobum''s hardiness rating actually means

Yes — polystichum setiferum 'divisilobum' is genuinely cold hardy. Rated RHS H5 and USDA 5-8 (hardy evergreen fern), 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 5-8 (hardy evergreen fern) — 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. Polystichum setiferum 'Divisilobum' is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for polystichum setiferum 'divisilobum' 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 polystichum setiferum 'divisilobum' go outside or overwinter — and where?

Plant it out within USDA 5-8 (hardy evergreen fern) 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 polystichum setiferum 'divisilobum' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Polystichum setiferum 'Divisilobum' hardiness — frequently asked questions

Is polystichum setiferum 'divisilobum' cold hardy?

Yes — polystichum setiferum 'divisilobum' is genuinely cold hardy. Rated RHS H5 and USDA 5-8 (hardy evergreen fern), it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Polystichum setiferum 'Divisilobum' is hardy across USDA 5-8 (hardy evergreen fern); 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 polystichum setiferum 'divisilobum' can survive?

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

What hardiness zone is polystichum setiferum 'divisilobum'?

Polystichum setiferum 'Divisilobum' is rated USDA 5-8 (hardy evergreen fern) and RHS H5 — Hardy in most of the UK and in cold winters.

Can polystichum setiferum 'divisilobum' survive winter outside?

Plant it out within USDA 5-8 (hardy evergreen fern) 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 polystichum setiferum 'divisilobum' 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.