Is this plant a weed?

Yes, it is widely considered a persistent and invasive weed in gardens and agricultural fields.

How do I get rid of it?

You must remove the entire root system, as even small fragments left in the soil can sprout new plants.

Plant guide

Perennial sowthistle.

Sonchus arvensis

Pronounced SON-kus ar-VEN-sis

Also known as Corn Sow Thistle, Creeping Sowthistle, Field Sow Thistle, Field Sowthistle, Field sow-thistle

This hardy perennial is often considered a persistent weed in gardens and agricultural fields. It spreads through an extensive underground root system that makes it quite tough to remove once established. You will recognize it by its bright yellow, dandelion like flowers and milky sap.

At a glance

Care level: Easy
Plant type: Perennial herb
Light: Full sun
Indoor light: Direct sun
Water: Every 7 to 14 days
Mature size: 5 feet
Growth rate: Fast
Hardiness: USDA 3 to 9
Bloom time: Mid summer to early autumn

Care

This plant thrives in full sun and tolerates a wide variety of soil conditions. Keep an eye out for rapid spread, as it can quickly crowd out other plants in your garden. Regular removal of the entire root system is necessary if you want to keep it contained.

Watering: It is quite drought tolerant once established but prefers consistent moisture.
Feeding: It does not require supplemental fertilizer and often thrives in nutrient rich soil without help.
Pruning: Deadhead flowers before they go to seed to help prevent unwanted spreading.
Repotting: If growing in a container, move to a larger pot when the roots become crowded.
Soil: Well draining soil
Soil pH: 6.0 to 7.5
Temperature: -40 to 30°C
Humidity: 40 to 70%
Drought tolerance: Moderate
Lifespan: Perennial, typically 3 to 5 years.
Deer and rabbits: Moderate

Signs it needs repotting

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

Safety

People: There is no significant toxicity reported for humans.
Children: The plant is not inherently dangerous to children, but the milky sap can be sticky and messy.
Contact allergens: The milky sap can cause mild skin irritation in sensitive individuals.
Airborne allergens: The wind dispersed seeds may cause minor irritation for those with severe allergies.
Edibility: While the young leaves are edible, they can become bitter and tough as the plant matures.

How to identify it

Bright yellow dandelion like flower heads
Leaves have spiny, irregular toothed margins
Stems contain a milky white sap
Grows from deep creeping rhizomes

Height: 0.3 to 1.5m
Spread: 0.3 to 0.6m
Leaves: green, blue-green, deciduous
Flowers: yellow, 3 to 5cm
Fruit: brown, late summer

Problems to watch for

Aphids · Small insects that cluster on the undersides of leaves and stems.
Powdery mildew · A fungal infection that creates a white dusty coating on the foliage.

By symptom

Plant problems by symptom

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Growing it

Propagation: seed, division
When to plant: spring, autumn
Overwintering: The plant dies back to the ground in winter. The root system remains dormant underground until spring.
In containers: It is not recommended for containers due to its aggressive root system and tendency to become invasive.

Division

1. Dig up the root system in early spring.
2. Separate the roots into smaller sections.
3. Replant the sections in a new location.

Because this plant is highly invasive, it is best not to include it in any intentional garden guild.

Similar species

Common sow thistle · It is an annual relative that looks very similar but lacks the deep creeping roots.

Science

Family: Asteraceae
Genus: Sonchus
Order: Asterales
Class: Magnoliopsida
Native range: Europe and western Asia.
Conservation: It is considered an invasive weed in many regions outside its native range.

It thrives in disturbed soils and open fields where it can outcompete other vegetation with its rapid growth.

Value to wildlife: nectar source
Pollinators: bees, butterflies
Uses: foraging, wildlife habitat

Through the year

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Flowering

Fruiting

Foliage

Ecological indicators

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

Taxonomy resolved against GBIF.

Questions people ask

Is this plant a weed?: Yes, it is widely considered a persistent and invasive weed in gardens and agricultural fields.
How do I get rid of it?: You must remove the entire root system, as even small fragments left in the soil can sprout new plants.

Where the name comes from

The scientific name Sonchus arvensis translates to sow thistle of the fields.

Good to know

The name Sonchus comes from the Greek word for hollow, referring to the stems.
It is often mistaken for a dandelion until it grows much taller.
The seeds are equipped with a feathery pappus that helps them travel long distances on the wind.

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This guide was generated with AI on October 19, 2026 and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.