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Oregon · Washington · Idaho

When to plant sword fern

Plant in the garden: Portland and Seattle Mar 1 – Apr 26; Spokane Apr 1 – May 27; Boise Mar 20 – May 15; Bend Apr 28 – Jun 23.

Western sword fern is a large native evergreen fern with stiff, dark green fronds up to 4 or 5 feet long. It's one of the most common plants on Northwest forest floors and is grown for year-round green in shade gardens. The fronds are also cut and sold as florist greenery.

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Puts sword fern on your free plan, with dates for your town and a spot in your beds.

Difficulty
Easy
Sun
Part to full shade
Spacing
2 to 3 feet apart
Planting depth
Crown at soil level; don't bury it
Frost
Hardy perennial; comes back every year
First harvest
Evergreen fronds all year

The big evergreen fern of west-side forests. It thrives in shade under trees where little else grows. Water it through its first summers; established ferns in deep shade need little help, but they suffer in long droughts.

Sword fern planting dates

TownsPlant in the garden
Portland, OR, Seattle and Tacoma, WAMar 1 – Apr 26
Spokane, WAApr 1 – May 27
Boise and Meridian, IDMar 20 – May 15
Bend and Redmond, ORApr 28 – Jun 23
Astoria, ORMar 25 – May 20

Dates for six main cities. For any of the other 80 towns, type it in the box at the top of the page or browse all towns.

Sword fern year at a glance

TaskJFMAMJJASOND
PlantMarApr

Around Portland. Colder towns, especially east of the Cascades, run a few weeks later; the table above has your town's planting dates.

How to grow sword fern

  1. Pick a shady spot, such as under trees or on the north side of a building, and mix in leaf mold or compost.
  2. Plant sword ferns on your city's dates, 2 to 3 feet apart. Crown at soil level; don't bury it.
  3. Water through the first two summers. Leave fallen leaves around the crowns as mulch.
  4. Harvest: Enjoy the evergreen fronds all year. Cut off old, tattered fronds in early spring, just before the new fiddleheads unroll.

Growing sword fern in your part of the Northwest

The same plant behaves differently on the wet west side, the foggy coast and the dry, colder east side.

West-side valleys

Willamette Valley, Puget Sound, southern Oregon

Sword fern is one of the most common west-side forest plants and handles dry summer shade once established.

Coast

Oregon and Washington coast

Sword fern thrives in the coastal climate and can take more sun there.

East of the Cascades

Columbia Basin, Yakima, Boise, Spokane, north Idaho

Sword fern needs shade and regular water east of the Cascades; hot sun burns the fronds.

More sword fern varieties

More widely sold picks that do well somewhere in the Northwest. The tag says which part of the Northwest suits each one best.

Western sword fern

Native evergreen fern (Polystichum munitum) · Evergreen

The big forest fern of western Oregon and Washington. Buy nursery-grown plants rather than digging them from the wild.

West side

How much to grow

How many to plant

Plant 3 or more, 3 to 4 feet apart. A mature fern is about 4 feet wide.

Key numbers

Top care tip: Water deeply in long droughts and leave fallen leaves around the crown as mulch.

Growing notes

What makes the difference in Northwest gardens, in plain language.

The fern of west-side forests

Western sword fern is the large evergreen fern that carpets forests in western Oregon and Washington. Its dark green fronds stay fresh all winter, which makes it one of the most useful plants for shady yards.

It's long-lived and grows into a big clump over time.

Planting

Plant in part to full shade, such as under trees or on the north side of a building, in soil rich in organic matter. Set the crown at soil level; buried crowns can rot.

Water through the first two summers. Established ferns in shade with leaf mulch need little help, but sword ferns have been dying back in some Puget Sound forests after hot, dry summers, so water deeply during long droughts, especially if they're in sun.

Care

In early spring, before the new fiddleheads unroll, cut off old, tattered fronds at the base. Leave healthy fronds, which feed the plant.

Let fallen leaves stay around the crown as mulch. Sword ferns need no fertilizer.

Good neighbors

Grows well with

  • Salal and huckleberries. The same shady woodland soil.
  • Oregon grape. Also takes dry shade under trees.

Pests and problems

What most often goes wrong with sword fern in Northwest gardens, how to spot it and what to do.

Drought stress

Signs: Fronds brown at the tips in sun or dry soil.

What to do: Keep it in shade, mulch with leaves and water in long dry spells.

Tattered old fronds

Signs: Ragged brown fronds in spring.

What to do: Cut them off just before new fiddleheads unroll.

Sword fern dieback

Signs: In some Seattle-area forests, whole stands have died since 2013.

What to do: The cause is still being studied. Water garden ferns in long dry spells and report patches of dying ferns to your local native plant society.

Common questions about growing sword fern

When should I plant sword fern in Oregon, Washington and Idaho?

Plant in the garden: Mar 1 – Apr 26 in Portland and Seattle, Apr 1 – May 27 in Spokane, Mar 20 – May 15 in Boise and Apr 28 – Jun 23 in Bend. Pick your town at the top of the page for your own dates.

Can sword fern grow in sun?

In cool coastal gardens, some. Inland, sun and dry soil scorch the fronds. Shade is best.

Should I cut back my sword fern?

Remove old, tattered fronds in early spring before new growth unrolls. It isn't required, but it keeps the plant tidy.

Why are my sword fern fronds turning brown?

Usually drought or too much sun. Water deeply in dry spells, mulch with leaves and keep it in shade.

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