Flowering rush

Flowering rush: how do you recognise it?

Habit

A clump of narrow, upright leaves with flower stems up to 1 m tall.

Leaves

Long, narrow and linear, triangular in cross-section, often slightly twisted at the tip.

Flower

Umbels of dozens of pink flowers 2–3 cm across, with three petals and three sepals, from June to August.

Stem

Bare, round and sturdy, with the umbel at the top.

Roots

A creeping rhizome with small bulbils, by which the plant spreads.

Flowering: June–August · Plants: April–June · Pruning: March, August and October

Why grow it?

• Beautiful pink flower umbels held high above the water, from June to August.
• A native plant for the wildlife pond, attracting bees and hoverflies.
• The long, straight stems are ladders for dragonfly larvae and perches for adult dragonflies.
• Grows in shallow water 5–30 cm deep, where few other plants flower so well.
• Fully hardy and easy: dividing it every few years keeps it flowering freely.

Flowering rush: where does it grow best?

• Full sun: in shade it hardly flowers.
• In shallow water 5–30 cm deep, or in the wet marsh zone.
• Loam, clay or peat, neutral to chalky.
• Allow 40–50 cm per plant, and in a small pond one aquatic basket per plant.

Light

Sun

Soil type

Loam, clay or peat

Acidity

Neutral or chalky

Moisture

Wet

Size

1 m tall, 0.5 m wide

Hardiness

Hardy (to -30 °C)

Goes well with

• Water plantain: Airy white flower sprays beside the pink umbels.
• Yellow flag: Flowers yellow in May–June, just before the flowering rush.
• Purple loosestrife: Purple-pink spikes on the wet bank at the same time.
• White water lily: Floating flowers in the deeper water behind.
• Water forget-me-not: Small pale blue flowers along the shallow edge.

Flowering rush: when and how to plant it?

Plant in April–June.

1. Plant from April to June, as the water warms up.
2. Use an aquatic basket at least 25 cm wide filled with heavy, low-nutrient aquatic soil or clayey soil, without fertiliser or compost.
3. Lay the rhizome horizontally, 2–3 cm below the soil, with the leaves above, and firm in well.
4. Top with a layer of gravel against washing out and digging fish.
5. First set the basket 5–10 cm under water, then lower it after a few weeks to 30 cm at most.
6. Keep 40–50 cm between plants.

Care

Water

Must never dry out. In dry summers, top up the pond with rainwater.

Feeding

Not needed: fertiliser in the pond encourages algae.

Division

Divide every 3–4 years in spring, otherwise the clump becomes too dense and flowers less.

Deadheading

Cut the flower stems off at the base after flowering; this keeps the plant tidy.

Spread

Remove bulbils and runners growing outside the basket.

Tip: Plant it in full sun at a water depth of 5–30 cm and divide the clump every few years in spring: that keeps it flowering freely.

Flowering rush: when to prune it?

Pruning months: March, August and October.

When: Cut off the faded umbels in August. In October, cut the dead leaves off above the water, and the rest in March.

How:

• Cut the flower stems off at the base after flowering.
• Cut yellowed leaves back to a few centimetres above the water.
• In autumn, leave some foliage as shelter for insects and clear it in March.
• Always remove the cut leaves from the pond.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division

In April–May, lift the clump from its basket, cut the rhizome into pieces each with a few leaves and plant them separately.

Bulbils

In spring, detach the small bulbils from the rhizome and grow them on in a pot of wet aquatic soil, just under water.

Flowering rush: how does it get through the winter?

Hardy to −30 °C.

• Fully hardy, to about −30 °C: no protection needed.
• The foliage dies back in autumn; the rhizome overwinters in the mud.
• A basket 5–30 cm deep may freeze solid without harm.

Diseases and pests

• Few flowers: Too much shade, an overcrowded basket or planted too deep. Give full sun, divide the clump and raise the basket.
• Aphids: Aphids on young stems and leaves. Hose them off with pond water; natural predators do the rest.
• Crowded out: Vigorous neighbours such as common reed or bulrush smother it. Keep those in their own closed basket.
• Spreading bulbils: Bulbils come loose, float away and root elsewhere in the pond. Remove them and keep the plant in a basket.

Through the year

• March: Cut off old leaves.
• April: Plant or divide.
• May: Plant. Lower the basket after a few weeks.
• June: First flowers.
• July: Full flower. Top up the water in dry spells.
• August: Last flowers. Cut off faded umbels.
• October: Cut off dead leaves above the water.
• December: Rest.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Did you know?

• Flowering rush is the only species in its own plant family, the Butomaceae.
• Butomus comes from the Greek words for ‘ox’ and ‘to cut’: the sharp leaves were said to cut the mouths of grazing cattle.
• Thanks to the triangular cross-section of its leaves, you can recognise it even without flowers.