Autumn fern

Autumn fern: how do you recognise it?

Habit

Loose, rounded clump about 60 cm tall and as wide, with arching, obliquely upright fronds.

Fronds

Triangular to oval, twice divided, firm and glossy, 30–60 cm long.

Colour

Young fronds coppery red to orange-pink, later glossy green. They stay green in mild winters.

Spores

Round spore clusters under the frond, covered by a small membrane (indusium) that is red when young; ferns do not flower.

Roots

Short, creeping rhizome: the clump slowly widens but does not spread invasively.

Plants: March–May and September–October · Pruning: March

Why grow it?

• Colour in the shade: the coppery young fronds are a striking feature in spring.
• Glossy fronds that stay green in mild winters, so there is something to see in winter too.
• Grows in sand, loam and clay, as long as the soil is rich in humus and moisture-retentive.
• A neat, compact clump that does not spread: suitable for small gardens and for a large pot.
• Little work: cutting off the old fronds once a year is enough.
• Lovely beside flowering shade plants such as hellebores, hostas and barrenworts.

Autumn fern: where does it grow best?

• Partial shade to shade; morning sun is fine, but fierce midday sun scorches the fronds.
• Humus-rich soil: sand, loam or clay, acid to neutral. Improve heavy clay and poor sand with leaf mould.
• Moist but well drained: do not let it dry out, but avoid standing water too.
• Sheltered from drying winds, which turn the fronds brown, especially in winter.
• Plant 50–60 cm apart, or in a group of three at 50 cm.

Light

Partial shade and shade

Soil type

Sand, loam or clay

Acidity

Acid or neutral

Moisture

Normal

Size

0.6 m tall, 0.6 m wide

Hardiness

Hardy (to -25 °C)

Goes well with

• Hosta: Large, calm leaves beside the fine fern fronds, in the same partial shade.
• Hellebore: Flowers in late winter, around the time you cut off the old fern fronds.
• Japanese forest grass: A graceful, arching grass with fresh green to golden leaves, lovely beside the coppery young fronds.
• Barrenwort: A low, evergreen ground cover whose young leaves are often bronze-tinted too.
• Siberian bugloss: Sky-blue little flowers in April beside the orange-red young fronds.

Autumn fern: when and how to plant it?

Plant in March–May and September–October.

1. Plant from March to May or in September–October, when the soil is neither frozen nor too dry.
2. Loosen the soil and work in a few spadefuls of leaf mould or well-rotted compost.
3. Dig a hole twice as wide as the pot and set the plant at the same depth as before: the crown belongs at the surface, not below it.
4. Leave 50–60 cm between plants and firm the soil well.
5. Water thoroughly straight away and keep the soil moist for the first few weeks.
6. Spread a thin layer of leaf mould or fine wood chips around the plant, but not against the crown.

Care

Water

In the first year, water weekly in dry spells. After that only in long dry periods, in the morning at the base.

Feeding

Little needed: a layer of leaf mould or well-rotted compost in April is enough. No chemical fertiliser.

Mulching

Leave fallen tree leaves between the ferns in autumn: that is the best natural mulch.

Old fronds

Cut off the old fronds in March, before the new ones unfurl.

In a pot

A roomy pot with humus-rich compost and a drainage hole. Never let it dry out, and repot every two to three years in spring.

Tip: Cut the old fronds right off in March, even if they are still green: the coppery young fronds then stand out best. Out of drying winds, the foliage also looks better in winter.

Autumn fern: when to prune it?

Pruning months: March.

When: In March, before the new croziers unfurl. Otherwise this fern needs no pruning.

How:

• Cut the old fronds off just above the ground, even if they are still green: the coppery new fronds will then show off best.
• After a mild winter you can also just remove the brown and damaged fronds.
• Do not cut into the young, coiled croziers in the heart of the clump.
• Brown or damaged fronds can be removed now and then during the summer.

Caution: Do not wait until late April: once the new fronds are out, it is easy to cut them off by mistake.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division

In March–April, lift an older clump with several crowns and divide it with a sharp spade, each piece with a crown and roots. Replant at once and water well.

Spores

In late summer lay a ripe frond on a sheet of paper, sow the released spores on sterile, moist compost and cover with glass. It takes patience: small ferns only appear after several months.

Autumn fern: how does it get through the winter?

Hardy to −25 °C.

• Hardy to about −25 °C: no protection is needed in Belgian gardens.
• In mild winters the fronds stay green; after hard frost or dry east winds they turn brown, but the plant simply regrows in spring.
• Leave the old fronds until March: they protect the crown.
• In a pot: stand it against a sheltered wall and wrap it in hessian during severe frost.

Diseases and pests

• Brown fronds: Dry, brown frond edges from fierce sun, drying wind or drought. Water, mulch and if necessary move it to a more sheltered spot.
• Late frost: Young fronds can freeze and blacken in April–May. The plant regrows; cover with fleece if frost is forecast.
• Root rot: Yellow, limp plant in wet, compacted soil. Improve the soil with compost and coarse sand, or move it to a better-drained spot.
• Vine weevil: Mainly in pots, the grubs eat the roots and the plant wilts for no obvious reason. Check the root ball and use nematodes against the grubs in late summer.

Through the year

• March: Cut off the old fronds. Spread leaf mould.
• April: Coppery new fronds. Plant or divide. Watch out for late frost.
• May: Plant. Water in dry spells.
• June: Fronds turn green. Water in dry spells.
• July: Water in dry spells. Remove brown fronds.
• August: Water in dry spells. Collect ripe spores.
• September: Plant. Collect ripe spores.
• October: Plant. Leave fallen leaves between the ferns.
• December: Rest. In mild winters the fronds stay green.

Did you know?

• ‘Erythrosora’ means ‘with red sori’: the membranes covering the spore clusters are bright red when young.
• The genus name Dryopteris comes from the Greek ‘drys’ (oak) and ‘pteris’ (fern), after the woodlands where many species grow.
• Ferns do not flower or set seed: they reproduce by spores as fine as dust.