Dwarf hard fern

Dwarf hard fern: how do you recognise it?

Habit

Low, creeping carpet 10–15 cm tall that spreads by rhizomes to 50 cm or more.

Fronds

Narrow, comb-like, cut into short rounded lobes; leathery and dark green.

Fertile fronds

Upright, narrower fronds that rise above the foliage and carry the spores on their underside.

Colour

Young fronds bronze to reddish, later dark green and glossy.

Roots

Creeping, shallow rhizomes that slowly form a dense carpet.

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

Why grow it?

• An evergreen ground cover for shade that covers the soil all year.
• Bronze to red new fronds in spring and summer: a warm colour among the green.
• Low and fine: lovely at the front of a border, between stones, along paths or under rhododendrons.
• Hardy to about −20 °C, so it needs no protection in most Belgian winters.
• Little upkeep: a single tidy-up a year is enough.

Dwarf hard fern: where does it grow best?

• Partial to full shade; it tolerates some sun if the soil stays moist.
• Humus-rich, acid to neutral soil: sand, loam or peat, improved with leaf mould. It dislikes lime.
• Moist but well drained: no drying out, but no waterlogging in winter either.
• Sheltered from cold, drying winter winds.
• Plant 25–30 cm apart for a carpet that closes quickly.

Light

Partial shade and shade

Soil type

Sand, loam or peat

Acidity

Acid or neutral

Moisture

Normal

Size

0.15 m tall, 0.5 m wide

Hardiness

Hardy (to -20 °C)

Goes well with

• Rhododendron: Likes the same acid, humus-rich soil; the fern covers the ground beneath it.
• Japanese maple: The low fern as a carpet under a graceful small tree.
• Hosta: Large leaves above the fine, low carpet.
• Snowdrop: Flowers early in spring through the evergreen carpet.
• Wood anemone: Small white flowers in April above the dark green carpet.

Dwarf 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 not frozen or too dry.
2. Loosen the soil and work in leaf mould; on chalky soil you are better off choosing another fern.
3. Set the plants at the same depth as in the pot, with the rhizomes just below the surface.
4. Leave 25–30 cm between plants and firm the soil well.
5. Water well straight away and keep the soil moist for the first few weeks.
6. Spread a thin layer of leaf mould or pine needles between the plants.

Care

Water

Regularly in dry spells in the first year. Later only in long dry periods.

Feeding

A thin layer of leaf mould in spring is enough; no lime and no chemical fertiliser.

Mulching

Fallen tree leaves can stay on the carpet; they keep the soil rich in humus.

Weeding

Weed between the plants in the first year, until the carpet has closed.

Tidying

In March, cut off damaged or brown fronds so the new bronze fronds show well.

Tip: Give it acid to neutral, humus-rich soil: on chalk it fades away. Leave fallen autumn leaves on the carpet and the soil will enrich itself.

Dwarf hard fern: when to prune it?

Pruning months: March.

When: In March, once the worst frosts are over. Otherwise it needs no pruning.

How:

• Cut brown, frost-damaged fronds off close to the ground.
• Healthy green fronds can stay.
• If the carpet has spread too far, chop off the edges with a spade in spring.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division

In March–April, cut pieces of the carpet with rhizome and roots and replant them elsewhere straight away. This is easy.

Spores

In summer, collect ripe spores from the upright fertile fronds and sow them under glass on sterile, acid seed compost.

Dwarf hard fern: how does it get through the winter?

Hardy to −20 °C.

• Hardy to about −20 °C: no protection needed in most Belgian winters.
• In hard frost the fronds may turn brown; the rhizomes regrow in spring.
• In hard frost without snow, you can cover the carpet for a while with conifer branches or fleece.
• In a pot it is more vulnerable: stand the pot sheltered against a wall and wrap it in hessian.

Diseases and pests

• Yellow fronds: On chalky soil the fronds turn yellow and the plant grows poorly. Improve the soil with leaf mould or choose another spot.
• Drying out: Brown frond edges and stalled growth in drought or too much sun. Water and mulch.
• Frost damage: Brown fronds after a hard winter. Cut them off in March; the plant usually regrows.
• Weeds: Grass and weeds grow through the young carpet. Hand-weed until the carpet has closed.

Through the year

• March: Cut away brown or damaged fronds. Spread leaf mould.
• April: Plant or divide. New bronze fronds appear.
• May: Plant. Weed between young plants.
• June: Water in dry spells.
• July: Water in dry spells. Collect ripe spores.
• September: Plant or divide.
• October: Plant. Leave fallen leaves on the carpet.
• December: Rest. Cover if needed in hard frost without snow.

Did you know?

• ‘Penna marina’ means ‘sea feather’ in Latin, after the shape of the comb-like frond.
• Like many ferns in its family, it has two kinds of fronds: ordinary fronds and separate, upright spore-bearing fronds.
• In its homeland it also grows high in the mountains and on cold, windswept islands near Antarctica.