Petty spurge

Euphorbia peplus

In other languages: Tuinwolfsmelk (Nederlands) · Euphorbe des jardins (Français)

Grows wild in Belgium.

Petty spurge is a small, fresh green annual with a conspicuous white milky sap. It is very common throughout Belgium in vegetable plots, borders, flowerpots, between paving stones and in arable fields: anywhere the soil is bare, loose and rich. You can recognise it by its hairless, upright little stems with small, rounded leaves and by its green ‘flowers’ with crescent-shaped glands bearing two horns. Snap a stem and out comes a sap that strongly irritates the skin and especially the eyes. In a wildlife garden it is a modest plant: small flies, tiny parasitic wasps and ants take its nectar, and ants carry its seeds away.

Caution: Poisonous. The white milky sap strongly irritates the skin and eyes and can cause blisters and painful inflammation of the eye; eating it is also harmful. Children who pick plants or play on the ground, and pets and grazing animals that nibble it, are most at risk. Wear gloves when weeding, never rub your eyes and wash your hands after contact. If sap gets into your eyes, rinse them immediately with plenty of water and see a doctor.

Updated on 9 October 2026

Light
Sun or partial shade
preferably some sun
Moisture
Normal
no wet feet
Hardiness
down to -15 °C
protect young plants
Size
0.25 m
tall, 0.2 m wide
Flowering
March–November

Key facts
Height	0.25 m
Native to Belgium	Yes
Flowering	March–November

Identify

How to recognise it

Habit: Annual, 10–30 cm tall, hairless and pale green; a single straight stem or branched from the base.
Leaf: Small, oval to obovate, 1–3 cm, with a short stalk and a smooth edge; scattered along the stem.
Flower: An umbel of three rays that branch further. Each ‘flower’ is a small cup (cyathium) with four greenish, crescent-shaped glands with long, thin horns.
Fruit/Seed: A hairless capsule of 2 mm with three valves, each with two narrow wings on its back. The grey seeds are pitted and carry a white appendage.
Stem: Round and hairless; snap it and white, sticky milky sap appears at once.
Look-alikes: Sun spurge is sturdier and yellow-green, with a five-rayed umbel, finely toothed leaf tips and oval glands without horns. Dwarf spurge has narrow, linear leaves. Purslane looks similar from a distance but has fleshy leaves and no milky sap.

Flowering: March–November

In your garden

Why grow it?

Flowers from early spring to late autumn, offering nectar to small flies, tiny parasitic wasps and ants.
Ants spread the seeds: each seed has a small white, nutritious appendage that attracts them.
A fascinating little plant for looking closely, with a hand lens, at the strange flower structure of spurges.
Shallow-rooted, so it is easy to pull up where you do not want it.
A useful indicator: where it grows abundantly, the soil is loose, bare and rich.

Petty spurge: where does it grow best?

In the wild on bare, disturbed ground: vegetable plots, arable fields, borders, nurseries, planters and the cracks between paving stones.
Likes rich, loose soil that is regularly cultivated; in a closed lawn it disappears.
Sun to partial shade; it also grows in the shade of vegetables and perennials.
Normal, moisture-retentive soil; in dry summers it stays small and sets seed quickly.

Goes well with

Common chickweed: Grows on the same bare, rich soil and provides seed for finches and sparrows.
Red dead-nettle: Also flowers early in the year, with nectar for bumblebees and bees.
Common field-speedwell: Little blue flowers in the same spring greenery of vegetable plot and border.
Shepherd’s-purse: Another small pioneer of bare soil, with seed for birds.

Maintenance

Petty spurge: when and how to plant it?

There is no need to plant it: petty spurge arrives by itself, with potting compost, with bought plants and via ants.
If you want to give it a spot, leave a few plants in a corner of bare soil, away from paths, the sandpit and play areas.
You can sow in March–April or in September: scatter the seed thinly on loose soil and press it in. It germinates after a few weeks.
Leave 15–20 cm between plants; watering is only needed in a pot that dries out.
Wear gloves when moving or weeding plants, and wash your hands straight afterwards.
Never dig up plants from the wild: take seed from your own garden or from someone you know.

Care

Watering: Not needed; it copes, even in dry soil. In drought it simply stays smaller.
Feeding: Not needed: it already grows vigorously in rich soil.
Weeding: Pull or hoe young plants before they flower, ideally after a shower when they come out easily. Always wear gloves.
Spreading: It self-seeds freely and has several generations a year. A mulch of leaf mould, straw or grass clippings between the vegetables keeps most of it away.
Letting it seed: If you want to keep it, let a few plants set seed in one fixed corner and weed out the rest in time.

Tip: Always weed petty spurge with gloves on and before the capsules are ripe: your hands stay unharmed and the seed bank in your soil stays small.

Pruning and mowing

When: No pruning: it is an annual. Weed out unwanted plants from March to November, before they set seed.

How:

Pull the plant up roots and all; it is shallow-rooted and comes out easily.
Do it before the capsules are ripe: they burst open and shoot the seeds away.
Put weeded plants without seed on the compost heap; plants with ripe seed belong in the green waste collection, not on a cold compost heap.

Caution: Wear gloves and do not touch your eyes while weeding: the milky sap is caustic.

Pruning calendar and basic rules

Propagation

Seed: It spreads only by seed. The capsules burst open and ants carry the seeds further. The seed stays viable in the soil for years and germinates almost all year round as soon as the soil is disturbed.

Petty spurge: how does it get through the winter?

Hardy to −15 °C: protect young plants.

In mild winters the plants stay green and even keep flowering.
Hard frost kills the plants, but the seed in the soil survives and germinates again in spring.
Lots of petty spurge in winter points to bare soil: a mulch or green manure protects the soil better and keeps it in check.

Diseases and pests

Sap on the skin: Can cause redness, itching and blisters, especially in sunshine. Wear gloves when weeding and wash your skin with soap and water.
Sap in the eyes: Very painful and harmful to the eye. Never rub your eyes with sap on your hands; rinse immediately with plenty of water.
Too many seedlings: In vegetable beds and window boxes it can form a carpet. Weed early, mulch the soil and do not let any plants set seed.
Arriving with plants: It often turns up in the pots of bought plants. Remove it straight away, before it sets seed.
Confusion with edible plants: Young plants can come up among purslane or lettuce. Never pick anything you do not know: you can tell a spurge by its milky sap.

Through the year

February: In mild winters the first plants are already flowering.
March: Seedlings appear: weed them out between the seed rows. You can sow if you want a few plants.
April: Flowering. Mulch between the vegetables.
May: Flowering and seed set. Weed before the capsules ripen.
June: After hoeing and harvesting, a new generation germinates.
July: Flowering. Weed with gloves on.
August: The capsules burst open; ants carry off the seed.
September: Flowering. You can sow; let a few plants set seed in a corner.
October: Sow a green manure on empty beds so that fewer seeds germinate.
November: Last flowers until the first frost.

You and this species

Did you know?

What looks like a single flower is a cyathium: a small cup with glands containing a group of much-reduced male flowers and a single female flower.
The genus Euphorbia is named after Euphorbus, physician to King Juba II of Mauretania, around the beginning of the Common Era.
In folk medicine the sap was once dabbed on warts. This is not advisable: the sap is caustic.

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