Is Sonchus oleraceus a weed?

Yes, it is widely considered an agricultural and garden weed due to its rapid growth.

Yes, young leaves are often eaten raw in salads or cooked like spinach.

Plant guide

Common sowthistle.

Sonchus oleraceus

Pronounced SON-kus oh-ler-AY-see-us

Also known as Common Sow-Thistle, Common Sowthistle

Common Sow-thistle — Photo by Gavin Slater (CC BY) via iNaturalist

This common plant is a hardy annual that often pops up as a weed in gardens and disturbed soil. It produces yellow, dandelion-like flowers and has milky sap inside its stems. While many consider it a nuisance, it is actually edible and has a long history of use in foraging.

At a glance

Care level: Easy
Plant type: Annual herb
Light: Full sun to partial shade
Indoor light: Direct sun
Water: Every 3 to 7 days
Mature size: 3 to 4 feet
Growth rate: Fast
Hardiness: USDA 6 to 10
Bloom time: Spring to autumn

Care

This plant is quite resilient and typically manages itself in most outdoor environments. Watch for aphids or powdery mildew if you are growing it in a container. It thrives best when it has plenty of space and consistent access to sunlight.

Watering: Keep the soil consistently moist but not waterlogged for best growth.
Feeding: A balanced liquid fertilizer can be applied occasionally if the soil is poor.
Pruning: Deadhead spent flowers to prevent unwanted seed spread throughout your garden.
Repotting: Since it is an annual, you will generally be replanting it from seed each season.
Soil: Well-draining, fertile soil
Soil pH: 6.0 to 7.5
Temperature: -5 to 35°C
Humidity: 30 to 80%
Drought tolerance: Moderate
Lifespan: Annual, typically 6 to 9 months.
Deer and rabbits: Moderate

Signs it needs repotting

Roots growing out of the drainage holes.
Stunted growth despite regular watering.

Safety

People: It is generally considered non toxic to humans.
Children: There are no specific safety concerns for children, though the milky sap can be messy.
Contact allergens: The milky sap can cause mild skin irritation in sensitive individuals.
Airborne allergens: Pollen may cause mild allergic reactions in susceptible people.
Edibility: While young leaves are edible, older leaves become bitter and may contain high levels of nitrates if grown in nitrogen rich soil.

How to identify it

Yellow dandelion like flower heads
Leaves with prickly, toothed margins
Hollow, brittle stems with milky sap
Basal rosette of lobed leaves

Height: 0.3 to 1m
Spread: 0.2 to 0.5m
Leaves: green, blue-green, deciduous
Flowers: yellow, 1.5 to 2.5cm
Fruit: brown, Summer to autumn

Problems to watch for

AphidsCommon
Powdery MildewCommon
RustUncommon
Slugs and SnailsUncommon

By symptom

Plant problems by symptom

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Growing it

Propagation: seed
When to plant: spring, autumn
Overwintering: It usually dies back after the first hard frost, so no special care is needed.
In containers: It grows easily in pots, but is rarely cultivated intentionally due to its weedy nature.

Seed

Collect seeds from mature flower heads once they turn fluffy.
Scatter seeds on moist soil in early spring.
Keep the soil lightly moist until germination occurs.

Keep it away from your primary vegetable beds to prevent it from becoming a nuisance.

Grows well with

Lettuce · They share similar growing requirements.

Similar species

Dandelion · Both have yellow flowers and similar rosette growth habits.
Prickly Sow Thistle · It looks very similar but has sharper, pricklier leaf edges.

Science

Family: Asteraceae
Genus: Sonchus
Order: Asterales
Class: Magnoliopsida
Native range: Europe, North Africa, and Western Asia.
Conservation: It is a widespread weed and is not of conservation concern.

It thrives in disturbed habitats like roadsides and gardens where it quickly outcompetes other plants for light.

Value to wildlife: nectar source, larval host plant
Pollinators: bees, butterflies, beetles
Uses: edible greens, poultry feed, medicinal tea

Through the year

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Flowering

Fruiting

Foliage

Ecological indicators

Salinity: 2/9
Soil reaction: 6/9
Light: 7/9
Temperature: 6/9
Moisture: 5/9
Nutrients: 7/9

Taxonomy resolved against GBIF.

Questions people ask

Is Sonchus oleraceus a weed?: Yes, it is widely considered an agricultural and garden weed due to its rapid growth.
Can I eat it?: Yes, young leaves are often eaten raw in salads or cooked like spinach.

Where the name comes from

The genus name Sonchus comes from the Greek word for hollow, referring to the stems, while oleraceus means vegetable or garden herb.

Good to know

Commonly known as sow thistle because it was traditionally fed to nursing sows.
The leaves are often compared to dandelion greens in flavor.
It is a highly successful colonizer of disturbed soils worldwide.
The plant contains a milky latex sap that flows when stems are broken.

Keep your common sowthistle growing

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This guide was generated with AI on September 26, 2026 and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.