Hard fern

Hard fern: how do you recognise it?

Habit

A low, open rosette 30–40 cm tall and up to 50 cm across, from a short, upright rhizome.

Fronds

Narrow, leathery, glossy dark green and deeply cut into narrow segments like the teeth of a comb; spreading to arching.

Fertile fronds

From summer, upright fronds with very narrow segments appear in the centre, carrying the spores underneath. They die off during the winter.

Roots

A compact rhizome with fine roots; it does not send out runners.

Flowers

None: ferns do not flower and reproduce by spores.

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

Why grow it?

• Green all year: even in winter its rosette of glossy fronds looks good.
• A native species, ideal for a wildlife garden or woodland planting.
• Thrives in shade and on acid soil, where many plants struggle.
• A lovely contrast between the spreading, comb-like fronds and the upright fertile fronds.
• Stays compact and does not spread: suits small gardens, edges and pots.
• Almost no work: removing old fronds once a year is enough.

Hard fern: where does it grow best?

• Partial to full shade; in full sun the fronds scorch and the soil dries out too fast.
• Acid, humus-rich soil: sandy or peaty, with plenty of leaf mould. It does not tolerate lime.
• Moist to wet, but not standing water; the soil should never dry out completely.
• A sheltered spot under trees or shrubs, out of drying winds.
• Allow 40–50 cm between plants; it looks best in groups of three or five.

Light

Partial shade and shade

Soil type

Sand or peat

Acidity

Acid

Moisture

Normal or wet

Size

0.4 m tall, 0.5 m wide

Hardiness

Hardy (to -25 °C)

Goes well with

• Rhododendron: The same acid, humus-rich soil; the fern covers the bare base of the shrub.
• Pieris: An evergreen shrub for acid soil, with sprays of white flowers in spring.
• Wood anemone: A native spring flower that blooms white among the ferns.
• May lily: A low native ground cover of acid woodland, with small white flowers in May.
• Heather: On the sunnier edge of a heather garden, in the same acid soil.

Hard 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 moist and not frozen.
2. Dig a hole twice as wide as the root ball and mix in leaf mould or ericaceous compost.
3. Set the plant at the same depth as in the pot: the crown with the young curled fronds should sit just above the soil.
4. Firm in and water well straight away, preferably with rainwater.
5. Spread a 5 cm mulch of leaf mould, pine needles or fine bark around the plant.

Care

Watering

Water regularly in dry spells during the first year. Use rainwater if you can: hard tap water raises the pH.

Feeding

Not needed. A layer of leaf mould in spring provides enough nutrients.

Mulching

Leave fallen tree leaves around the fern, or spread some leaf mould or pine needles every spring.

Old fronds

In March, cut damaged or brown fronds off at the base, before the new ones unfurl.

Moving

Possible in spring or autumn with a good root ball; it re-establishes quickly.

Tip: In dry summers, water with rainwater and mulch with pine needles or leaf mould: this keeps the soil acid and moist, and the fronds a fresh green.

Hard fern: when to prune it?

Pruning months: March.

When: In March, just before the new fronds unfurl. Real pruning is not needed: you only tidy up old foliage.

How:

• Cut brown, damaged or flattened fronds off close to the base.
• Leave healthy green fronds: they stay attractive for another season and protect the crown.
• Remove last year’s dead fertile fronds.
• Take care with the young curled fronds in the crown: they snap easily.

Caution: Never cut the whole plant back at once and leave the crown alone: that is where the new fronds come from.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division

In April, lift an older clump with several crowns and split it with a spade or knife into pieces, each with a crown and roots. Replant at once and water well.

Spores

In late summer or autumn, let ripe fertile fronds dry in a paper bag. Sprinkle the spores on moist, acid seed compost, cover with glass or plastic and keep in the light but out of the sun. After a few months a green film appears; the young ferns follow later.

Hard fern: how does it get through the winter?

Hardy to −25 °C.

• Fully hardy to about −25 °C: no protection needed in Belgium.
• The fronds stay green in winter; leave even discoloured ones until March, as they protect the crown.
• A layer of fallen leaves around the base keeps the soil moist and protects against hard frost.
• In a pot: stand it in a sheltered corner and water now and then when it is not freezing, as the root ball must not dry out, even in winter.

Diseases and pests

• Brown edges: A sign of drought, bright sun or drying wind. Water, mulch and choose a shadier spot.
• Yellow fronds: Often caused by lime in the soil or the water. Water with rainwater and mulch with acid leaf mould or pine needles.
• Slow growth: On poor, dry sandy soil it stays small. Work leaf mould into the top layer every year.
• Vine weevil: In pots the grubs eat the roots: the plant wilts for no obvious reason. Nematodes against the grubs work well, applied in spring or late summer.

Through the year

• March: Cut old and brown fronds off at the base. Spread leaf mould. Plant.
• April: The new fronds unfurl. Plant or divide.
• May: Plant. Water in dry spells.
• June: The first fertile fronds appear in the centre.
• July: Water in dry spells, preferably with rainwater.
• August: Collect ripe spores for sowing.
• September: Plant. Collect and sow ripe spores.
• October: Plant. Leave fallen leaves around the base.
• December: Rest. The green fronds brighten the winter garden.

Did you know?

• Its Dutch name, dubbelloof (‘double foliage’), refers to its two kinds of frond: spreading sterile fronds and upright fertile ones.
• It also grows wild on the west coast of North America, where it is called deer fern.
• Botanists now often place it in a separate genus, as Struthiopteris spicant.