Spinulose wood fern

Sun

Partial to full shade; tolerates some morning sun where the soil stays moist.

Water

Keep the root zone consistently moist, especially during establishment; avoid prolonged drought and stagnant, waterlogged soil.

Soil

Humus-rich, moist soil, preferably acidic to neutral; tolerates clay if it is not compacted or persistently waterlogged.

Height

1.5-3 ft (0.45-0.9 m)

Spread

1.5-2.5 ft (0.45-0.75 m)

Foliage

Upright to arching, narrowly triangular fronds, finely divided into toothed leaflets with tiny bristle-tipped teeth. Usually deciduous, though some fronds may persist through mild winters.

Growth

Moderate

Care needed

Low

• Deer resistant
• Cold hardy
• Wildlife
• Low allergen

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Easy

Toughness

Fairly tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   1 ft (0.3 m)

2. After 1 year

   1.4 ft (0.43 m)

3. After 2 years

   1.8 ft (0.55 m)

4. After 3 years

   2.2 ft (0.68 m)

   full size

About 3 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Toxic

Native to

the US, Canada and the UK

Growth rate

Moderate

• Water deeply during dry spells before the soil around the roots dries out.
• Apply a thin layer of leaf mould or compost each spring, keeping the crown uncovered.
• Mulch with shredded leaves to conserve moisture and protect shallow roots.
• Avoid routine high-nitrogen feeding; an annual compost dressing is usually enough.
• Divide established clumps in early spring only when you need more plants.

Pruning. In late winter or early spring, cut dead and damaged fronds close to the base before new fiddleheads unfurl. Leave healthy green fronds in place and avoid cutting into the crown.

Late winter

Remove collapsed fronds if they obscure the crown; leave any healthy green growth.

Early spring

Plant or divide clumps as growth begins, setting the crown at its previous soil level.

Spring

Top-dress with leaf mould or compost and check that emerging fiddleheads are not being eaten.

Summer

Check soil moisture during hot or dry weather and water thoroughly when needed.

Autumn

Plant while the soil is moist and still warm, allowing time for roots to establish before hard frost.

Late autumn

Retain a loose layer of fallen leaves around the clump, without burying the crown.

• Plant in loose groups beneath deciduous trees to create a layered woodland floor.
• Pair with hostas or large-leaved brunneras for contrast between fine and bold foliage.
• Use beside a shaded path where the arching fronds can soften its edge.
• Plant on the moist upper bank of a pond or stream, above the permanently saturated zone.

Garden styles it suits: Woodland, Wildlife garden, Secret garden, Green on green, Low-maintenance and Moss and fern garden.

Plant it with: Hostas, Siberian bugloss, Foamflower, Solomon's seal, Astilbes and Sedges.

Wildlife: Clumps provide sheltered, humid cover for small invertebrates and other woodland wildlife. The plant has no flowers and supplies neither nectar nor pollen.

• Brown, brittle frond edges usually indicate drought or drying wind; water deeply, renew mulch and provide a more sheltered position.
• Yellowing and crown decay can follow stagnant wet conditions; improve drainage and keep soil or mulch off the crown.
• Slugs and snails may damage emerging fiddleheads; inspect young growth and hand-pick pests on damp evenings.
• Pale or scorched foliage can result from excessive sun, especially in hot climates; move the plant into afternoon shade.

Species-specific toxicity information for people, cats, dogs and horses is limited, so it should not be assumed safe to eat. Related wood ferns contain poisonous compounds, particularly in their rhizomes, and ingestion can be serious. Do not eat the fiddleheads or allow pets or livestock to graze the plant.

• Intermediate wood fern (Dryopteris intermedia)

  On the lowest main leaflet, the first small leaflet on the lower side is shorter than the next one in intermediate wood fern; in spinulose wood fern it is usually longer.

• Broad buckler fern (Dryopteris dilatata)

  Usually has broader, more triangular fronds and stalk scales with a conspicuous dark central stripe. Spinulose wood fern has narrower fronds and mostly uniformly pale brown stalk scales.

• Marginal wood fern (Dryopteris marginalis)

  Has thicker, leathery, evergreen fronds with round spore clusters close to the leaflet margins. Spinulose wood fern has softer, more finely divided fronds, with spore clusters set farther inward.

The common name refers to the tiny spine-like tips on the leaflet teeth, while carthusiana refers to the Chartreuse region of France.

Propagation. Divide established clumps in early spring, keeping roots and at least one healthy growing point on each division. It can also be raised from ripe spores sown on a clean, moist medium under cover, but this is slow and requires careful hygiene.

Accepted botanical name

Dryopteris carthusiana

In the US and Canada

Native in Canada, the lower 48 states and St. Pierre and Miquelon.

Native range

Alabama, Albania, Alberta, Altay, Arkansas, Austria, Baltic States, Belarus, Belgium, British Columbia, Bulgaria and Buryatiya.

Measured

Soil pH 5 to 5.5. Average height 59 cm.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.