Skip to main content
Dryopteris crassirhizoma (Thick-stemmed Wood Fern)
1 / 9
© Peter Zika, some rights reserved (CC-BY-NC) · iNaturalist
Ferns

Dryopteris crassirhizoma

Thick-stemmed Wood Fern

Dryopteridaceae
Eastern Asia (Japan, Korea, northeastern China, Russian Far East; moist mountain forests and rocky woodland margins)

Learn more

At a Glance

TypeFern
HabitClumping
FoliageSemi-evergreen
Height24-36 inches (60-90 cm)
Width24-36 inches (60-90 cm)
Maturity4 years

Growing Zones

USDA Hardiness Zones

4 - 8
Zone 4Zone 5Zone 6Zone 7Zone 8
These zones indicate the coldest temperatures this plant can typically survive.
What's my zone? →
Frost Tolerancehardy

Key Features

Deer ResistantContainer Friendly
Maintenancevery low

Overview

Dryopteris crassirhizoma is a large upright vase-shaped semi-evergreen fern in the wood-fern family (Dryopteridaceae) reaching 24–36 inches (60–90 cm) tall with a spread of 24–36 inches (60–90 cm). This East Asian species forms a stout erect crown — the specific epithet 'crassirhizoma' references this thick-rhizome structure — from which the bipinnate fronds emerge in a symmetrical vase-shaped rosette. Fronds are 24–36 inches (60–90 cm) long and 8–12 inches (20–30 cm) wide, medium to dark green, with a firm leathery texture that separates this species from the thinner-frond wood ferns in cultivation. New fiddleheads in spring are densely covered in cinnamon-brown to golden-brown scales, producing a spring ornamental feature that precedes the frond expansion by 2–3 weeks. Fronds are bipinnate with broad triangular pinnae. The plant is semi-evergreen: fronds persist through mild winters but tatter by late winter in cold-zone gardens and are removed before new growth starts. Growth rate is moderate. The thick crown develops a short stocky trunk 4–6 inches (10–15 cm) tall over 5–8 growing seasons. Hardy to zone 4.

Native Range

Dryopteris crassirhizoma is native to eastern Asia (Japan, Korea, northeastern China, and the Russian Far East), where it occurs in moist mountain forests and rocky woodland margins.

Suggested Uses

Grown in shade gardens, woodland borders, and foundation plantings at 24–30 inch (60–75 cm) spacing. The large vase-shaped form carries architectural structure in shade compositions where few other plants match the scale. Cinnamon-brown fiddleheads add spring interest at a time when most shade perennials have not yet emerged. Functions as a specimen fern or in groups of 3–5 plants. Pairing with Hosta cultivars, Astilbe, and other shade perennials builds a layered shade-garden composition. Deer resistance suits woodland plantings in high-pressure garden sites. Full-sun positions, dry soils, and poorly-drained planting sites are not suitable given the moisture and shade requirements.

How to Identify

Separated from D. cycadina by the broader more triangular frond outline (versus the narrower more lance-shaped outline of D. cycadina) and by the cinnamon-brown fiddlehead scales (versus the dark brown to near-black scales of D. cycadina). Separated from D. lepidopoda by the larger mature size at 24–36 inches (versus 18–24 inches for D. lepidopoda), by the green new growth (versus the copper-orange new growth of D. lepidopoda), and by the vase-shaped habit (versus the arching habit of D. lepidopoda). Separated from D. filix-mas by the thicker crown structure, by the more leathery frond texture, and by the more prominent cinnamon-brown fiddlehead scaling. A large vase-shaped fern carrying a thick crown, leathery bipinnate fronds, and cinnamon-brown scaled fiddleheads confirms identification.

Appearance

Size & Dimensions

Height2' - 3'
Width/Spread2' - 3'

Reaches mature size in approximately 4 years

Colors

Foliage Colors

green

Fall Foliage Colors

no change

Bloom Information

Ferns do not flower. Sori (spore-producing structures) appear as round clusters on the undersides of fertile fronds in summer, covered by kidney-shaped indusia. New fiddleheads emerge in spring densely covered in cinnamon-brown to golden-brown scales that hold through the 2–3 week unfurling period and fade as the fronds expand to full size.

Detailed Descriptions

Foliage Description

Medium to dark green firm leathery bipinnate fronds; cinnamon-brown to golden-brown scaled fiddleheads in spring

Growing Conditions

Sun Requirements

Partial ShadeFull Shade
Requires 2-4 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.5 - 7.0(Neutral)
357912
Soil Types
loam
Drainagemoist

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

2-3 years

Care & Maintenance

Care Guide

Grows in partial to full shade in moist well-drained humus-rich soil at pH 5.5–7.0, tolerating loam. Hardy to zone 4. Consistent moisture is required through the growing season. The species tolerates more drought than many wood ferns once established, but the fronds read more vigorously in consistently moist soil than in drier planting contexts. Old tattered fronds are removed in late winter before new fiddleheads emerge to clear space for the spring crosier display. No serious pest or disease problems. Deer-resistant, which positions this fern for planting in wooded-lot gardens where deer pressure eliminates most non-fern shade perennials.

Pruning

Old tattered fronds are removed in late winter (February–March) before the new fiddleheads emerge. New crosiers are never cut back — the cinnamon-brown scaled fiddleheads are the spring ornamental feature and direct removal eliminates the display. No other maintenance is required through the growing season.

Pruning Schedule

J
F
M
A
M
J
J
A
S
O
N
D
winterearly spring

Maintenance Level

very low

Container Growing

✓ Suitable for container growing

Minimum container size: 5 gallons

⚠️ Toxicity Warning

Non-toxic