Sensitive fern
Onoclea sensibilis · Onocleaceae
Broad, light green fronds with wavy-edged lobes, more like a leaf than a fern. It is named for its sensitivity to the first frost. The beaded spore stalks stand all winter.
- Size
- 24 in tall, 3 ft wide
- Zones
- 3 to 9
- Light
- Part sun to shade
- Flowers
- Grown for its leaves
- Pets
- Toxic to horses
- Job in a bed
- Carpet
A bed built around sensitive fern
The planner designed this bed around sensitive fern when this page was made: a 12 × 6 ft (3.7 × 1.8 m) English border in zone 6, part shade. It chose the other plants from the 354 that suit those conditions and its wet soil, and says below why sensitive fern stands where it does.
The plants
- 1 Sensitive fern × 1, green leaves
- 2 Wherry's foamflower × 9, white
- 3 Blue star creeper × 19, blue
- 4 Northern sea oats × 5, tan
- 5 Foxglove × 4, purple
- 6 White bleeding heart × 1, white
- 7 Yellow trout lily × 12, yellow
- 8 Snowdrop × 12, white
Why this plant
- The only plant grown for its leaves. Leaf lasts all season, where a flower lasts a few weeks.
Why here
- In the middle. At 24 in it is the step between blue star creeper (3 in) in front and foxglove (4 ft) behind: each is seen over the one before.
- One plant. Three or more is usual for a plant of this kind, and reads better.
- Bold leaf against fine. Blue star creeper is beside it: the strongest contrast of leaf there is.
Why now
- Here for its leaves, spring to frost. They cover the 12 weeks between early March and late November when nothing on the plan is in flower.
Planned as an English border: 4 of the 5 groups (80%) are drifts, longer along the bed than they are deep. Northern sea oats and foxglove anchor the back corners of the bed: the tallest plants on the plan stand there. Cool colours (blue and purple) with yellow as the warm note, and white and tan to calm things between them.
The planner's own design check: 13 Excellent, 2 Good, 2 Satisfactory. It flags one thing to watch: Foxglove is highly poisonous to people, dogs, cats and horses. Sensitive fern spreads aggressively.
Open this bed in the planner Change its size, the sun or the style, move plants about, or swap one for another.
Where sensitive fern goes in a border
At 24 in it belongs in the middle of a bed. In the planner's ten height classes it is medium short (18 to 24 in).
Its job: carpet. A groundcover planted in threes and fives to cover the soil: along the front, and just behind it.
A coarse fern for wet ground where finer plants struggle. It spreads strongly, so use it for covering ground and not in a mixed bed.
- Wet soil and pond edges
- Covering large, damp areas
- Winter interest from the beaded stalks
What to plant with sensitive fern
Plants recorded as good partners for it, and what each pairing does:
- Cardinal flower: adds the flowers, late July to mid September; medium leaves against its bold ones; tall enough (3½ ft) to stand behind it.
- Marsh marigold: adds the flowers, mid April to early May; medium leaves against its bold ones; happy in the same wet soil.
- Turtlehead 'Hot Lips': adds the flowers, mid August to late September; medium leaves against its bold ones.
Questions about sensitive fern
Does sensitive fern need sun or shade?
Sensitive fern grows in part sun (4 to 6 hours of sun, including some afternoon sun), part shade (2 to 4 hours of sun, mostly in the morning) and shade (less than 2 hours of direct sun, or bright dappled light). It is one of the few that also put up with deep shade.
It wants moist to wet soil, rich in organic matter, and plenty of water.
What zones does sensitive fern grow in?
USDA zones 3 to 9. It is hardy to zone 3, which means it survives winter nights down to about −30 °F (−34 °C).
Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.
How far apart should sensitive fern be planted?
24 in (60 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 3 ft (90 cm), so a group knits into one patch.
It grows 24 in (60 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many sensitive fern plants do I need?
At 24 in apart, set out in staggered rows:
- 3 to fill 10 square feet (about 1 m²)
- 6 for a single row 10 ft (3 m) long
- 10 to fill a 4 × 8 ft bed on its own
In a mixed border, plant it as threes and fives, along the front and just behind it.
In the bed above, the planner used one in one group.
Is sensitive fern poisonous?
Yes: moderate toxicity to horses. Poisonous to horses if eaten in quantity, in pasture or in hay.
Rated from NC State Extension. Where references disagree, the more cautious rating is used.
Is there a native plant like sensitive fern?
Sensitive fern is not native to North America. These North American natives come closest to doing its job:
- Marsh fern: the same job in a bed and the same size; fine leaves, not bold.
- Netted chain fern: the same job in a bed; 4 in shorter, 12 in narrower.
- Hay-scented fern: the same job in a bed; 6 in narrower, fine leaves, not bold.
Matched the way the planner's Swap button matches plants: the same job in a bed, then size, then flowering time.
Do deer eat sensitive fern?
Mostly not. NC State lists it as resistant to deer. No plant is proof against a hungry deer in a hard winter, but this one is low on the menu.
Will sensitive fern spread?
It spreads sideways, by runners or roots; the risk of it taking over is high. Spreads strongly by underground runners in moist soil and forms large colonies. Give it room or a barrier.
What does sensitive fern look like in winter?
Sensitive fern dies down, but it is grown for winter interest from the beaded stalks, so leave it standing until early spring.
Is sensitive fern good for bees and butterflies?
Sensitive fern is visited by songbirds.
In these guides
- Plants for deep shade
- Plants for wet soil and rain gardens
- Deer-resistant plants for shade
- Plants that feed garden birds
- Groundcover plants
Zone guides: Zone 3 · Zone 4 · Zone 5 · Zone 6 · Zone 7 · Zone 8 · Zone 9
Every fact on record
- Type
- Fern
- Size
- 24 in (60 cm) tall, 3 ft (90 cm) wide
- Plant
- 24 in (60 cm) apart
- Height class
- Medium short (18 to 24 in)
- Place in the bed
- Middle
- Flowers
- None: grown for its foliage
- Leaves
- Bold texture, herbaceous; green
- Shape
- Upright, spreading
- Hardy in
- USDA zones 3 to 9
- Light
- Part sun, part shade, shade
- Soil
- Rich, moist to wet
- Water
- High
- Feeding
- None needed
- Family
- Onocleaceae
- Attracts
- Songbirds
- Stands up to
- Deer, deep shade
Checked against NC State Extension. Flowering times are for zone 5: later in colder zones, earlier in warmer ones. Toxicity and spread information is a general gardening guide, not veterinary or medical advice, and invasive status varies by region. If a person or pet eats a plant, contact poison control or a vet. Check your local invasive species list before planting anything with a spread warning.