Western sword fern (Polystichum munitum)

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Western sword fern

Habit (mature) · Jami Dwyer / Wikimedia Commons · CC BY-SA 2.0

Limited coverage

Western sword fern

Polystichum munitum

A Pacific Northwest evergreen fern with dark-green leathery fronds reaching 3-5 feet long — among the most iconic Pacific Northwest understory plants. Long-lived (decades), shade-tolerant, and one of the most reliable evergreen ferns for cool moist climates.

Native: 7 US states + 2 CA provinces

Review: Source-backed

Climate fit: moderate (54/100)

Structure

Filler

Light

Part sun / Part shade

Water

Consistent moisture

Mature size

36-60" tall · 36" apart

Hardy in zones

5a-9b

very cold to frosty winters

Summer heat range

Cool-Warm

cool to warm summers Interim Plotwright tier until the plant AHS range is authored.

Native in Illinois

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Native across 9 US states and Canadian provinces — a wide-ranging part of North America's plant communities.

Lady Bird Johnson Wildflower Center

Cold hardiness

Now

Zone 6b

USDA

Chicago, IL · 1991-2020 average annual coldest day

Source: USDA Plant Hardiness Zone Map 2023 (1991-2020 climatology) via ArcGIS FeatureServer

Well-suited

2050

Zone 7b

Plotwright

Your zone + climate-model shift · SSP3-7.0 (regional rivalry)

Well-suited

In plain terms: cold winters — coldest nights typically around -3°F.

✓

Well-suited today and still thriving in 2050.

Heat tolerance

°C

°F

Loading current AHS heat-zone and plant heat-fit data at your coordinates…

Where this plant fits

Suitable across 41 ecoregions — 39 climate-resilient through 2070 · 1 suited today · 1 newly possible by 2070. Best matches first.

Appalachian mixed mesophytic forests

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Appalachian-Blue Ridge forests

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Arizona Mountains forests

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Atlantic coastal pine barrens

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Blue Mountains forests

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Canadian Aspen forests and parklands

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Central Pacific Northwest coastal forests

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Central Tallgrass prairie

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Central-Southern Cascades Forests

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Chilean Matorral

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Sources & citations

Cite this page

For lesson plans, articles, or research that uses this page. To cite a single upstream fact instead, use its specific source listed below.

Plotwright. (2026, May 17). Western sword fern (Polystichum munitum). Retrieved 2026, June 5, from https://plotwright.garden/plants/western-sword-fern

Sources for every fact

Every fact on this page traces to a source. 18 fields cited — 18 source-backed.

NC State Extension Gardener Plant Toolbox

University extension service

Backs 17 fields

Identity

Summary

Plant type

Light

Moisture

Hardiness

Heat zone