Marsh woundwort

How to recognise it

Habit

Perennial, 40–100 cm, with upright, square, hairy stems. Forms patches through underground runners.

Leaf

Opposite, narrowly lance-shaped, 5–12 cm, finely toothed and softly hairy, stalkless or on a very short stalk. Smells faintly when crushed, far less unpleasant than hedge woundwort.

Flower

Lilac to pale purple, 12–15 mm, with a hood and a three-lobed lower lip marked with white, in whorls of six to ten flowers that together form a long spike. Flowers from June to September.

Fruit/Seed

Four smooth, dark nutlets per flower, inside the persistent calyx.

Roots

Creeping underground runners whose tips swell into small white tubers in autumn.

Confusion with

Hedge woundwort has broad, heart-shaped leaves on long stalks, dark wine-red flowers and a strong unpleasant smell when crushed; it grows in shade. Hybrids between the two occur. Water mint smells of mint and has rounded flower clusters.

Flowering: June–September · Pruning: March and September

Why grow it?

• Flowers from June to September: a rich source of nectar for bumblebees, other long-tongued bees and hoverflies in wet rough grassland.
• A sturdy, colourful plant for a pond edge or a wet corner, where many other flowers find it too wet.
• With its runners it forms attractive, dense patches that help hold a wet bank together.
• The dead stems and calyces give insects shelter in winter.
• The small tubers on the runners were once eaten, like those of its relative, Chinese artichoke.

Marsh woundwort: where does it grow best?

• In the wild along ditches, streams, rivers and ponds, in wet hay meadows, reed beds, at the edge of wet woodland and in damp fields.
• Sun to half shade.
• Moist to wet, rich soil: clay, loam or peat; it tolerates temporary flooding.
• In the garden: at a pond edge, in a bog strip or in a moist border that does not dry out.

Goes well with

• Purple loosestrife: Tall, purple-red spikes on the same wet bank, also in summer.
• Meadowsweet: Creamy, fragrant plumes in the wet corner.
• Yellow iris: Flowers earlier, in May–June, at the same pond edge.
• Hemp-agrimony: Pink flower heads for butterflies in the same rough patch.
• Yellow loosestrife: Yellow beside the lilac, in moist soil.

Marsh woundwort: when and how to plant it?

1. Buy pot-grown plants from a nursery for native or marginal plants.
2. Plant in March–May or September–October, 30–40 cm apart, in groups of three to five.
3. You can also sow: sow in autumn in a pot of moist compost left outdoors, so the seed gets a cold period. Prick out the seedlings in spring.
4. By a small pond: put the plant in a planting basket so the runners do not take over the whole bank.
5. Water well after planting and keep the soil moist during the first year.
6. Never dig up plants in the wild; ask someone who already has it for a piece of runner instead.

Care

Water

Not needed at the pond edge. In a border, water in dry spells: the soil must not dry out.

Feeding

Not needed; on soil that is too rich the stems become floppy and fall over.

Spreading

Spreads by runners. In spring or autumn, cut round the edges with a spade to keep the patch in check.

Mowing

Mow a wet rough area or bank once a year, in September, and remove the cuttings.

Leaving stems

Leave the faded spikes standing in winter: they give insects shelter.

Tip: By a small pond, grow marsh woundwort in a planting basket or in a strip you mow all round: you enjoy the flowers without the runners taking over the whole bank.

Pruning and mowing

Pruning months: March and September.

When: Cut the dead stems in March; mow a wet rough area or bank in September.

How:

• Leave the stems standing over winter: insects overwinter in and between the dead stems.
• Cut them close to the ground in March, before the new shoots appear.
• Mow a wet rough area in September and remove the cuttings, so the soil does not become too rich.
• When mowing, leave a strip uncut for overwintering insects.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division

In March–April or September–October, cut off pieces of runner with a few buds and replant them elsewhere.

Seed

Ripens in August–September. Sow in autumn in a pot left outdoors; it germinates after winter.

Tubers

You can dig up the small tubers on the runners in autumn and replant them straight away in a new spot.

Marsh woundwort: how does it get through the winter?

Hardy to −30 °C.

• The stems die back in autumn; the plant overwinters underground with runners and tubers.
• The dead stems with their calyces stay standing and shelter insects.
• Fully hardy, even in wet soil.

Diseases and pests

• Spreading: In wet, rich soil it can form a large patch. Cut round the edges or grow it in a planting basket.
• Flopping: On soil that is too rich or in shade the stems become floppy. Plant it in sun on unfertilised soil.
• Powdery mildew: White powder on the leaves in dry summers. More moisture and space help; cut out badly affected stems.
• Weed of damp fields: The runners are a nuisance in a damp vegetable garden. Do not rotavate, but carefully fork out the runners.
• Drought: It fades away in a dry border. Choose a spot that stays moist.

Through the year

• March: Cut dead stems. Plant or divide.
• April: New shoots appear. Cut round the edges.
• May: The stems grow fast; water in a dry border.
• June: First flowers; bumblebees visit the lilac whorls.
• July: Full flower at the pond edge.
• August: In flower; the seed starts to ripen.
• September: Last flowers. Mow the wet rough area; sow in a pot.
• October: Tubers form on the runners. Planting still possible.
• November: Leave dead stems standing for insects.

Did you know?

• The name woundwort recalls that the leaves were once laid on wounds.
• The tubers are edible and were eaten in the past; a related species from East Asia, Chinese artichoke or crosne, is still grown as a vegetable.
• Marsh woundwort and hedge woundwort sometimes cross; the hybrid shows features of both parents.