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Perennial · Euphorbiaceae
Marsh spurge
Euphorbia palustris
In other languages: Moeraswolfsmelk (Nederlands) · Euphorbe des marais (Français)
Marsh spurge is a large, native perennial of marshes, wet meadows and riverbanks in Europe; in Belgium it is rare in the wild. It forms broad clumps of sturdy, upright stems up to 1.2 m tall, with narrow, fresh green leaves. In May and June large lime-yellow flower heads appear above the foliage. In autumn the whole plant turns yellow, orange and sometimes red. Gardeners know it as one of the few spurges that tolerate wet feet; a well-known cultivar is ‘Walenburg’s Glorie’.
Caution: All parts are poisonous. The milky sap irritates skin and eyes and can cause vomiting and stomach pain if swallowed. Children, cats, dogs and grazing animals are at risk: do not plant it in a pasture or by a pond where livestock drink. Wear gloves and, if sap gets into the eyes, rinse immediately with plenty of water and seek medical advice.
Light
Sun or partial shade
preferably some sun
Moisture
Normal to wet
must not dry out
Legal basis
Loam, clay or peat
any pH
Hardiness
Fully hardy
down to -30 °C
Size
1.2 m
tall, 1 m wide
Flowering
May–June
| Pruning months | July and November |
|---|---|
| Height | 1.2 m |
| Native to Belgium | Yes |
| Good for bees, butterflies and birds | Yes, for bees |
| Poisonous to people and pets | Yes, take care with children and pets |
| Flowering | May–June |
Identify
Marsh spurge: how do you recognise it?
- Habit
- A broad, dense clump of sturdy, upright stems, 90–120 cm tall and up to 1 m wide.
- Leaves
- Narrowly lance-shaped, 4–7 cm, fresh green; yellow to orange-red in autumn.
- Flowers
- Large, widely branched heads with lime-yellow bracts, in May and June.
- Roots
- A thick, somewhat woody rootstock; the clump slowly widens.
- Sap
- White milky sap in all parts, irritating to skin and eyes.
Flowering: May–June · Plants: March–April and September–October · Pruning: July and November
In your garden
Why grow it?
- An architectural plant that gives the border structure from spring to autumn.
- Large lime-yellow flower heads in May–June that glow at the water’s edge.
- Striking yellow and orange autumn colour, when many other perennials have finished flowering.
- It tolerates wet soil: ideal at the edge of a pond or stream, or in a moist border.
- Native, and a source of nectar for bees and other insects.
Marsh spurge: where does it grow best?
- Full sun or light partial shade; in sun it stays sturdier and colours better in autumn.
- Loam, clay or peat, acid, neutral or chalky; humus-rich soil that holds moisture.
- Normal to wet soil, including the bank of a pond or stream where the ground stays wet.
- Allow 80–100 cm of space per plant: it grows wide.
- On dry soil it struggles in hot summers.
- Light
- Sun and partial shade
- Soil type
- Loam, clay or peat
- Acidity
- Not fussy
- Moisture
- Normal or wet
- Size
- 1.2 m tall, 1 m wide
- Hardiness
- Hardy (to -30 °C)
Goes well with
- Purple loosestrife: Purple spikes in summer, in the same wet soil.
- Meadowsweet: Creamy plumes and a fresh scent at the water’s edge.
- Siberian iris: Blue flowers in May–June, alongside the lime-yellow heads.
- Hemp agrimony: Pink flower heads in late summer that attract butterflies.
Maintenance
Marsh spurge: when and how to plant it?
Plant in March–April and September–October.
- Plant in March–April or September–October.
- Wear gloves to protect yourself from the sap.
- Dig a generous hole and mix in compost if the soil is poor.
- Set the plant at the same depth as it was in its pot and space plants 80–100 cm apart.
- Water in thoroughly straight away and keep the soil moist throughout the first year.
- Spread a layer of compost or leaf mould around the base.
Care
- Watering
- Not needed in a wet spot. Elsewhere, water generously in dry summers: in drought its leaves droop.
- Feeding
- A layer of compost in March is enough.
- Support
- Usually not needed; in a windy or too shady spot, a ring of twiggy sticks helps.
- Spent flowers
- Cut off the seed heads in July if you want to avoid seedlings; leave the leaves for autumn colour.
- Leave alone
- Let the clump grow undisturbed for years: it gets better every year.
Tip: Give it a spot at the edge of a pond or in a wet corner where other spurges would rot. Leave the stems standing until after the autumn colour: that is when it looks its best.
Marsh spurge: when to prune it?
Pruning months: July and November.
When: After flowering, in July, you can cut off the seed heads. After the autumn colour, in November, cut the stems down to ground level.
How:
- In July, remove only the spent tips, just above the leaves: it will self-seed less.
- Leave the leafy stems until after the autumn colour.
- In November, cut the dead stems down to 5–10 cm above the ground.
- Wear gloves and eye protection: the thick stems release a lot of sap.
Caution: Cutting the sturdy stems releases a lot of milky sap. Keep it out of your eyes and wash your hands afterwards.
Propagation
- Division
- In March–April, lift a clump and split it with a sharp spade into pieces with roots and buds. This is easiest with young plants.
- Seed
- Sow ripe seed in autumn in a pot outdoors; it often germinates only after a winter outside.
- Cuttings
- In April, take cuttings from young shoots at the base, dip the cut end in lukewarm water and insert in moist cutting compost.
Marsh spurge: how does it get through the winter?
Hardy to −30 °C.
- Extremely hardy, to about −30 °C: in Belgium it needs no protection.
- The stems die back after the autumn colour; in spring new shoots come up from the ground.
- Wet soil in winter is no problem for this spurge, unlike many other species.
- In a large pot or pond basket: make sure the soil does not dry out, even in winter.
Diseases and pests
- Drooping leaves: A sign of drought: water generously or move the plant to a moister spot.
- Powdery mildew: White powder on the leaves, especially in dry weather. Water and cut out affected stems.
- Aphids: On young shoots in May. Hose them off; ladybirds will do the rest.
- Seedlings: In wet places it self-seeds. Cut off the seed heads in July and weed out seedlings while young.
Through the year
- March: New shoots. Plant or divide. Add compost.
- April: Plant. Take cuttings.
- May: Flowering begins. Watch for aphids.
- June: Full flower. Water in dry weather.
- July: Cut off the seed heads.
- August: Water in dry weather, unless it grows in wet soil.
- September: Plant. Autumn colour begins.
- October: Full autumn colour. Plant. Sow seed outdoors.
- November: Cut back the dead stems.
Use
Edible and useful
Not edible. All parts of spurges contain a white, milky sap that is poisonous and caustic. On the skin it causes redness, itching and sometimes blisters; in the eyes it is extremely painful and can damage the cornea. Whenever you work on the plant, wear gloves, long sleeves and ideally safety glasses, do not rub your eyes, wash your hands and secateurs afterwards, and teach children not to break off the stems. If sap gets in your eyes, rinse them at once under running lukewarm water for at least a quarter of an hour and see a doctor. Swallowed, it burns the mouth and causes vomiting and stomach ache, in dogs and cats too; horses and livestock fall ill from it: never throw clippings into a field. If any is swallowed, call a poison centre (in Belgium 070 245 245) or your doctor at once.
Good for wildlife
- Bees
- Nectar and pollen for honeybees and wild bees.
You and this species
Did you know?
- Palustris means ‘of the marsh’: a reference to its natural habitat.
- It is one of the largest spurges growing wild in western Europe.
- In Belgium it grows wild mainly along rivers and in marshes, but it is rare there.