Groundsel

Senecio vulgaris

In other languages: Klein kruiskruid (Nederlands) · Séneçon commun (Français)

Grows wild in Belgium.

Groundsel is a small annual of the daisy family and one of the most common weeds in vegetable gardens, borders, fields and pavement edges. It grows throughout Belgium and flowers almost all year round, even in January in mild winters. You can recognise it by its small, cylindrical yellow flower heads without ray florets, whose bracts have black tips, and by the little white puffballs of its seed. A plant goes from seedling to seed in a few weeks, so there are several generations a year. It is poisonous to people and animals, but its seeds and flowers do have some value for birds and small insects.

Caution: Groundsel is poisonous because of pyrrolizidine alkaloids, which damage the liver and build up in the body. Horses, cattle, goats, rabbits and guinea pigs are most at risk, also through hay or feed containing dried plants. Do not let children eat it, do not give it to pets or cage birds, and keep it out of pastures and hay.

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, 0.15 m wide
Flowering
January–December

Key facts
Height	0.25 m
Native to Belgium	Yes
Flowering	January–December

Identify

How to recognise it

Habit: Annual of 10–40 cm, upright or somewhat spreading, often branched, with soft, slightly fleshy stems.
Leaf: Deeply cut into irregularly toothed lobes, slightly fleshy. The upper leaves clasp the stem. Hairless or with a few cobwebby hairs.
Flower: Yellow, cylindrical heads about 1 cm long, usually without ray florets, only disc florets. The bracts around the head have black tips. Flowers all year round.
Fruit/Seed: Nutlet with a white pappus; the ripe heads form little white puffballs carried off by the wind.
Roots: Small taproot; the plant is easy to pull up.
Confusion with: Sticky groundsel is sticky-hairy and has short, rolled-back ray florets. Narrow-leaved ragwort and common ragwort have conspicuous yellow ray florets and are much larger.

Flowering: January–December

In your garden

Why grow it?

Flowers almost all year, even in winter when hardly anything else is in bloom; flies and hoverflies sometimes take its pollen.
The seeds are food for finches, sparrows and other seed-eaters.
Food plant for a few moths, including the cinnabar moth, although that much prefers common ragwort.
To be honest: in the vegetable garden it is mainly a weed to keep in check. A few plants in a rough corner, away from animals and playing children, can stay for the birds.
A useful indicator: lots of groundsel points to bare, rich and often cultivated soil.

Groundsel: where does it grow best?

In the wild: fields, vegetable gardens, borders, waste ground, pavement edges, wall bases and compost heaps.
Sun to half shade.
Any bare, cultivated soil, preferably rich and moisture-retentive; it germinates fastest on bare soil.
In the garden it belongs, at most, in a rough corner, away from the vegetable patch, chickens, rabbits and horses.

Goes well with

Common chickweed: Another fast-growing plant of cultivated ground with seed for birds, for a rough corner.
Red dead-nettle: Early nectar for bumblebees on the same bare ground.
Shepherd’s purse: Another small field plant that flowers almost all year and sets seed.
Common poppy: Better still, choose a field margin with poppies: the same bare soil, but far more flowers for insects.

Maintenance

Groundsel: when and how to plant it?

There is no need to sow or plant it: groundsel arrives by itself, via wind, shoes, potting compost and imported soil.
If you want its seeds for the birds, leave a few plants in a rough corner out of reach of children and animals.
Weed out the rest as soon as you see them, preferably before they flower: young plants pull up easily.
Keep the soil covered with mulch or a green manure: on covered soil it germinates far less.
Check pot plants for seedlings before you put them in the garden.
Never dig plants up from the wild; for this species there is never any need.

Care

Weeding: Hoe every week in dry weather: the seedlings then dry out where they lie.
Plants in flower: Pull them up and take them away: even pulled plants can still ripen seed.
Mulching: A layer of compost, straw or grass clippings between the vegetables stops the seed from germinating.
Compost heap: Do not put flowering or seeding plants on a cold compost heap; if in doubt, put them in the green waste bin.
Feeding: Not applicable: it grows by itself on rich soil. Overfeeding makes the problem worse.

Tip: Hoe on a dry, sunny day and let the seedlings shrivel where they lie. Plants in flower go in a bag, because they still form seed after you have pulled them up.

Pruning and mowing

When: No pruning: weed before flowering, all year round.

How:

Hoe or pull up the plants before they flower.
Plants in flower or with pappus go in a bag, not on the compost heap.
Mowing helps little: it also flowers close to the ground.

Caution: Pulled plants that are in flower can still ripen seed on the ground, so do not leave them lying around.

Pruning calendar and basic rules

Propagation

Seed: Each plant produces hundreds of seeds with pappus, carried by the wind. It germinates almost all year and produces several generations a year; that is how it spreads, so do not let it flower where you do not want it.

Groundsel: how does it get through the winter?

Hardy to −15 °C: protect young plants.

Survives mild winters as a plant and simply keeps flowering.
Severe frost kills the plants, but the seed in the soil survives.
In winter one of the few flowering plants for early flies.

Diseases and pests

Groundsel rust: Orange pustules on the underside of the leaves, caused by a rust fungus. Remove affected plants.
Powdery mildew: White powder on the leaves, especially in late summer. Harmless, but weed the plant out.
Aphids: It can host aphids that move on to vegetables. Weed it out between the crops.
Rapid seeding: From seedling to seed in a few weeks. Weed every week.
Poisonous in fodder: Poisonous to animals, even dried in hay. Keep it out of pastures, hay meadows and animal feed.

Through the year

January: Flowers in mild winters. Weed in dry weather.
March: First big flush of seedlings on bare soil. Hoe.
April: In flower. Weed before the puffballs appear.
May: Mulch between the vegetables.
June: Flowers and seed. Take away plants in flower.
August: Watch for rust and mildew on the leaves.
September: New seedlings after harvest. Sow a green manure.
October: In flower. Weed.
December: Keeps flowering in mild weather.

You and this species

Did you know?

The name Senecio comes from the Latin ‘senex’, old man: the white seed puffballs look like a grey head of hair.
A plant can go from seedling to seed in a few weeks, so several generations follow each other within a single year.
The orange groundsel rust now seen on many plants originally comes from Australia and only appeared in Europe around 1960.

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