Common club-rush

Common club-rush: how do you recognise it?

Habit

Upright, dense stand of round stems up to 2 m tall; with its rhizomes it spreads to 80 cm across and more.

Stems

Round, smooth and dark green, up to 1.5 cm thick at the base, filled with airy, spongy tissue.

Leaves

Hardly visible: the leaves are reduced to sheaths at the base of the stems.

Spikelets

Small reddish-brown spikelets in a tuft just below the tip of the stem, in summer; not showy.

Roots

Thick, creeping rhizome that spreads strongly.

Pond zone

Deeper margin: from 20 to 100 cm below the water surface.

Plants: April–June · Pruning: March

Why grow it?

• Clean, round stems up to 2 m: a strong vertical line in a large pond.
• Helps to clean the water: bacteria living among the roots break down waste, and the plant takes up nutrients that would otherwise feed algae.
• Birds find shelter in the dense stands, and moorhens and coots take cover there.
• Dragonflies and damselflies climb out of the water up the stems to emerge.
• Also grows 50–100 cm deep, where few other marginal plants will.
• Native and fully hardy.

Common club-rush: where does it grow best?

• Sun to partial shade.
• A bottom of loam, clay or peat; acid, neutral or alkaline all suit it.
• Water depth 20–100 cm in still or slow-moving water; young plants shallower at first.
• Only in a larger pond, or in a container in a smaller pond, as it spreads strongly.
• Allow at least 80 cm per plant.

Light

Sun and partial shade

Soil type

Loam, clay or peat

Acidity

Not fussy

Moisture

Wet

Size

2 m tall, 0.8 m wide

Hardiness

Hardy (to -30 °C)

Goes well with

• Water lily: Round floating leaves and flowers in front of the straight stems, in deep water.
• Yellow water lily: A native floating-leaved plant with yellow flowers for deep water.
• Yellow flag: Yellow flowers in May–June in the shallower zone in front.
• Flowering rush: Pink flower heads in shallow water, in summer.

Common club-rush: when and how to plant it?

Plant in April–June.

1. Plant from April to June, when the water warms up.
2. In a smaller pond use a sturdy container of at least 20 litres filled with heavy clay soil, without potting compost or fertiliser.
3. Lay the rhizome about 5 cm deep and top with 2–3 cm of gravel.
4. Stand the container at 10–20 cm depth first and lower it after a few weeks to 20–100 cm below the water surface.
5. Keep at least 80 cm from other plants.

Care

Water

Not needed in the pond. In dry summers top up the pond with rainwater.

Feeding

Do not feed: it takes its nutrients from the water, and that is exactly its job.

Keeping in check

In summer dig or cut out rhizomes that grow outside the container.

Tidying

In autumn remove fallen stems from the water.

Dividing

Every 3–4 years, when the container is overfull, divide in April–May.

Tip: In a smaller pond always plant it in a sturdy container: you get the fine, straight stems without it taking over the whole bank.

Common club-rush: when to prune it?

Pruning months: March.

When: In March, before the new stems appear. Leave the old stems standing all winter.

How:

• Cut all old, brown stems off just above the water surface.
• Remove broken stems that hang in the water as early as autumn.
• In summer you can cut out some of the stems if the stand gets too dense.

Caution: Do not cut too late in March: the new stems grow fast and are easily damaged.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division

In April–May take the plant out of its container and cut the rhizome with a sharp spade or saw into pieces with a few stems each. Plant straight away in a new container.

Common club-rush: how does it get through the winter?

Hardy to −30 °C.

• Fully hardy, to about −30 °C: no protection is needed in Belgium.
• The stems turn brown in autumn. Leave them until March: insects overwinter in them and birds shelter among them.
• The rhizome overwinters safely in the bottom under the ice.

Diseases and pests

• Spreading too much: New stems far outside the container or along the whole bank. Dig out rhizomes and divide the container every few years.
• Broken stems: Wind, ice or snow break the stems. Remove what hangs in the water; cut everything back in March.
• Brown tufts: Brown tufts at the top of the stems in summer are the spikelets: not a disease.
• Small pond overrun: The stand takes over the open water. Then choose a container, or the smaller grey club-rush.

Through the year

• March: Cut old stems off above the water surface.
• April: Plant or divide. The new stems appear.
• May: Plant. Set the container at the right depth.
• June: Planting is still possible. The stems grow fast.
• July: Dig out rhizomes outside the container.
• August: Top up the pond in dry spells.
• October: Take fallen stems out of the water.
• December: Leave the stems standing as winter shelter.

Good for wildlife

Birds

Berries, seeds or insects as food, or a place to nest.

Did you know?

• The stems were once woven into mats, baskets and chair seats: its Dutch name means ‘mat rush’.
• The spongy tissue in the stems is full of tiny air channels that carry air down to the roots in the oxygen-poor mud.
• Common club-rush is used in reed-bed filters that clean waste water.