Sensitive fern

Sun

Partial to full shade; tolerates more sun where the soil stays consistently wet.

Water

Keep consistently moist to wet. Established plants tolerate waterlogged soil but not prolonged drought.

Soil

Humus-rich, moist or wet soil, preferably acidic to neutral; tolerates clay.

Height

2-3 ft (0.6-0.9 m)

Spread

3-5 ft (0.9-1.5 m), eventually wider through creeping rhizomes

Foliage

Broad, triangular, light-green sterile fronds with deeply divided, rounded lobes. Separate, narrow fertile fronds carry bead-like spore-bearing structures that turn brown and remain after the leafy fronds die.

Growth

Fast in moist, fertile soil

Care needed

Low

• Deer resistant
• Cold hardy
• Heat tolerant
• Wildlife

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

   1.7 ft (0.53 m)

3. After 2 years

   2.5 ft (0.75 m)

   full size

About 2 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 and Canada

In the garden

Spreads vigorously: plan to contain it.

Growth rate

Fast

• Water during dry spells before the soil dries out around the roots.
• Apply leaf mould or compost as a surface mulch in spring.
• Avoid routine fertiliser; an annual organic mulch is usually sufficient.
• Lift unwanted rhizomes in spring to keep the patch within bounds.
• Divide crowded or oversized patches in spring as new growth begins.

Pruning. Cut collapsed leafy fronds to ground level after autumn frost or before new growth in spring. Leave the brown fertile stems through winter for structure, then remove them if desired.

Early spring

Remove old fronds before the new shoots expand.

Spring

Plant or divide into moist soil and water thoroughly.

Late spring

Mulch with leaf mould or compost, keeping emerging shoots uncovered.

Summer

Water during dry weather and remove rhizomes spreading into neighbouring plants.

Autumn

Allow frost-blackened foliage to collapse; retain fertile stems for winter interest.

• Use in broad drifts beneath deciduous trees where the soil remains damp.
• Plant along pond margins above the permanent waterline for bold, soft-green foliage.
• Combine with sedges and moisture-loving perennials in a rain garden's damp lower areas.
• Use as a spreading groundcover in a large woodland garden, away from delicate plants.

Garden styles it suits: Woodland, Bog garden, Wildlife garden, Green on green, Rewilded and Japanese.

Plant it with: Hostas, Astilbes, Rodgersias, Turtlehead, Japanese primroses and Sedges.

Wildlife: Dense patches provide cover for small animals and invertebrates. It produces neither flowers nor nectar, so it is not a direct food source for pollinating insects.

• Unwanted spread: lift creeping rhizomes regularly or choose a bed with firm boundaries; avoid planting beside small, slow-growing perennials.
• Brown, scorched fronds in summer: restore consistent moisture and provide more shade, especially in hot climates.
• Slug or snail damage to emerging fronds: check young growth and remove pests by hand or use an appropriate labelled control.
• Blackened foliage after frost: this is normal seasonal dieback, not usually disease; remove collapsed fronds when convenient.

Reported poisonous to horses and other grazing livestock; keep them away from the fronds and prevent fern material entering hay. Poisoning can be serious. Toxicity to cats and dogs is not well established, so do not assume it is safe to chew. It is not an edible fern for people; do not eat the young shoots or other parts.

Where it spreads. Can spread aggressively by rhizomes in damp gardens in eastern North America, the United Kingdom and other suitable cool-temperate regions. Its vigorous garden spread does not necessarily mean it is officially listed as invasive locally.

• Netted chain fern (Woodwardia areolata)

  Its leafy fronds have more pointed, finely toothed lobes. Its fertile fronds carry elongated, chain-like spore cases rather than the rounded beads of sensitive fern.

• Ostrich fern (Matteuccia struthiopteris)

  Forms upright, vase-shaped crowns of finely divided, feather-like fronds rather than broad, triangular fronds on a spreading patch.

• Cinnamon fern (Osmundastrum cinnamomeum)

  Has finely divided leafy fronds and conspicuous cinnamon-brown fertile fronds, without sensitive fern's bead-like segments.

The common name and the Latin epithet sensibilis refer to the leafy fronds' sensitivity to frost.

Propagation. Divide rhizomes in spring, keeping roots and at least one growing point on each piece; replant promptly and keep moist. It can also be raised from spores, but this is slower.

Accepted botanical name

Onoclea sensibilis

In the US and Canada

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

Native range

Alabama, Amur, Arkansas, China North-Central, China Southeast, Chita, Colorado, Connecticut, Delaware, District of Columbia, Florida and Georgia.

Measured

Average height 50 cm.

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