Ornamental · Dryopteridaceae
Autumn Fern
Dryopteris erythrosora
In moist shade, the autumn fern unfurls copper-red new fronds that catch the light blade by blade.
Partial shade
Every 5–7 days
USDA 5–9
18–30 in · 45–76 cm
Overview
The autumn fern is a tough woodland fern from East Asia, prized for the copper-red color that washes over its new fronds. Each crozier uncoils bronze to orange-red in spring, the young blades thin and glinting, then the color sinks into a glossy deep green as the season runs on. The clump holds its arching shape through the cold and stays evergreen in milder gardens.
Up close the foliage is finely cut, the fronds divided into many small leaflets that give the whole plant a soft, lacy texture. Give it the shade and steady moisture it likes and little else is asked of it, and once settled it shrugs off dry shade and short dry spells better than most ferns. Deer tend to pass the clump by.
One trait shows below the soil rather than in the blades: the fern travels by creeping underground rhizomes and can spread further than expected. North Carolina Extension flags it as potentially weedy, so check regional guidance before planting.
Care
The short version: part to full shade in rich, humusy soil kept evenly moist. Water it through the first season to get the roots going, clear the old fronds in late winter, and the glossy green clump largely looks after itself from there.
Light
Give it part to full shade, the dappled light of a woodland floor that keeps the blades a clean green. It takes some morning sun, but harsh afternoon light scorches the fronds to pale, brittle edges unless the soil stays reliably moist.
Water
Keep the soil evenly moist, above all through the first growing season while the roots establish. Watering every 5 to 7 days suits most spots, and once settled the fern handles short dry spells and dry shade better than most.
Soil
Plant it in humus-rich, well-drained loam packed with organic matter. A slightly acidic pH of 5.0 to 6.5 suits it best, and plenty of leaf mold or compost keeps the ground moist without turning soggy.
Temperature
It is hardy and cold-tough, taking winters down to -20°F (-29°C) and warmth up to around 86°F (30°C). That range covers USDA zones 5 through 9, where the blades stay evergreen at the milder end.
Humidity
Average humidity around 40% to 70% keeps the fine leaflets supple and uncurled. Like most ferns it dislikes dry air, so a shaded, sheltered spot with moist soil does more for it than chasing any single humidity number.
Feeding
This is a light feeder, so don't overdo it. A spring topdress of compost or leaf mold feeds it well, or use a balanced slow-release fertilizer once as the new croziers start to rise.
Pruning
It barely needs cutting back. In late winter to early spring, before the new fronds unfurl, clear away any tattered, old, or winter-damaged fronds to make room for the fresh blades.
Repotting
If you grow it in a container, repot every 2 to 3 years, or when roots push from the drainage holes and the soil dries out fast. A crowded rhizome lifting at the surface is another sign it needs more room.
Size & spacing
Expect an arching clump 18 to 30 inches (45 to 76 cm) tall that spreads its fronds 24 to 35 inches (60 to 90 cm) wide. Leave room for that spread, and keep in mind it can creep further by rhizome over time.
When to plant
The autumn fern carries no flowers to time and no harvest to gather, so planting is the only date that matters. Set it out in spring once the frost has passed, or in early autumn while the soil still holds enough warmth for the roots to settle before winter.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: Spring after last frost, or early autumn
Hardiness
USDA hardiness zones: 5–9
Temperature: down to -29°C
Troubleshooting
Almost every problem with this fern is written on the fronds themselves, in pale patches, ragged edges, or fading color, and most trace back to too much sun, too much wind, or the wrong amount of water. Read the blades and the fix usually follows. Match your symptom below and act before more fronds turn.
Fronds bleaching pale, edges browned and crisp
Pale, papery patches and crisp brown rims along the fronds are sun scorch, and they usually arrive when the soil has gone dry, showing worst on the blades caught in hot afternoon light. Move the plant into deeper shade or cast some cover over it, then water deeply and mulch to hold that moisture in the ground. Cut away the browned fronds and fresh green ones unfurl to replace them.
Fix:
- Relocate or shade plants receiving harsh afternoon sun
- Water deeply and mulch to retain soil moisture
- Trim badly damaged fronds to encourage fresh growth
Fronds paling to yellow as the clump sinks
When the deep green drains out of every frond and the whole clump pales, the cause is a moisture problem at the roots, working from one of two directions. Soggy, waterlogged soil drowns the roots, while soil that keeps drying out leaves them parched, so feel which way the ground leans before acting. Work organic matter into the soil or lift the fern off standing water for drainage, then hold an even, steady moisture that lets the color flood back into the blades.
Fix:
- Improve drainage by adding organic matter or relocating from standing water
- Establish a consistent watering routine to keep soil evenly moist
Frayed, ribbon-torn frond edges toward the wind
Strong, drying wind shreds the thin, finely cut blades, leaving the leaflet edges ragged and split along the side that faces the breeze, with no discoloration or pest marks to muddy the picture. Cut off the tattered fronds and give the plant a sheltered position or a windbreak. In a still, protected woodland corner the lacy foliage keeps its clean, intact outline.
Fix:
- Remove damaged fronds
- Provide a sheltered planting position or windbreak
Toxicity
No source confirms this fern is poisonous, and its close relatives like the Boston fern are listed as safe for pets. But no source confirms this exact species is safe either, so the honest answer is the data isn't there yet. Until it is, keep pets, livestock, and children from chewing the finely cut fronds as a sensible precaution.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Caution
No source names this fern as poisonous to cats, and close relatives like the Boston fern carry a safe listing. A cat that bites into the soft, finely cut blades may still drool or bring a little back up, so keep the fronds out of a cat's reach until the species is cleared.
Dogs Caution
Nothing on record marks this fern as harmful to dogs, and its shield fern relatives are counted non-toxic. A dog that chews the wiry stems and lacy leaflets could still get a mild stomach upset, which is reason enough to steer it away.
Horses Caution
No source settles whether this fern poses a risk to horses either way. Without that confirmation, keep grazing horses clear of the clump and watch for drooling or dullness if any of the foliage is eaten.
Rabbits Caution
Rabbits fall outside any toxicity entry for this fern, so its safety for them stays unproven. Offer none of the fronds, and treat a chewed blade as a cue to watch the animal.
Livestock Caution
Cattle, goats, and sheep have no documented reaction to this fern, helpful or harmful. Fence the clump off from grazing stock as a precaution rather than assume the foliage is safe.
Birds Caution
Nothing on record describes how birds handle this fern. Keep pet and backyard birds away from the fronds until a reliable source has its say.
People Caution
No part of this fern is meant to be eaten, and no source vouches for the blades as food. Keep children from chewing the fronds, and never treat it as a wild edible.
No documented toxicity, but no confirmed safety data for this exact species; discourage pets and children from chewing the fronds as a general precaution.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
A couple of named selections sit alongside the plain species, each differing in the color or cut of its blades.
'Brilliance'
Its new spring fronds open in a brighter, deeper red than the plain species, and the color clings to the blades further into the season.
var. prolifica
A narrow, finely cut form whose blades carry tiny plantlets along the frond stem, giving it a second way to spread on its own.
How to propagate
The autumn fern is simple to multiply, and dividing an established clump is by far the quickest way to raise more of the lacy fronds.
DivisionEasy
Spring or early autumn · 1 to 2 growing seasons
Division is the easy route. In spring or early autumn, lift an established clump and pull it into sections, keeping roots and a fan of fronds on each piece, then give the divisions a season or two to settle in and fill out. New plants will also rise from the spores that ripen orange-red on the frond undersides, though that path runs much slower and asks for more patience.
Myths
Fronds glowing copper in autumn gave the fern its name.
The coppery bronze to orange-red color glows on the new fronds as they unfurl in spring, then sinks into a glossy deep green by summer. The name describes spring, not fall. What turns orange-red in autumn is the ripe spores studding the undersides of the fronds.
Every last fern is toxic to cats as well as dogs.
Plenty of true ferns in the same family, the Boston fern and sword fern among them, are listed as non-toxic to pets by the ASPCA. But no source confirms the status of this exact species, so the safe move is to keep pets from chewing the fronds rather than assume it follows its relatives.