It is best to wear gloves when handling it to avoid skin irritation.

Does it spread easily?

Yes, it produces thousands of wind dispersed seeds.

Plant guide

Common ragwort.

Jacobaea vulgaris

Pronounced ja-ko-BEE-uh vul-GAIR-iss

Also known as Common Ragwort, St. James'-wort, Stinking willie, Tansy ragwort

Jacobaea vulgaris — Photo by R Mitchell (CC BY) via gbif

This hardy biennial is a familiar sight in meadows and pastures across Europe and parts of North America. It produces bright yellow, daisy like flowers that attract a wide variety of pollinators. While it is quite pretty, it is often considered a weed because it can be toxic to livestock.

At a glance

Care level: Easy
Plant type: Herbaceous biennial or short-lived perennial
Light: Full sun
Indoor light: Direct sun
Water: Every 7 to 14 days
Mature size: 1 to 4 feet
Growth rate: Fast
Hardiness: USDA 3 to 9
Bloom time: Mid summer to early autumn

Care

This plant thrives in full sun and well drained soil with little intervention. Keep an eye out for aphids or rust on the foliage during the growing season. It is a prolific seeder, so remove flower heads before they go to seed if you want to keep it contained.

Watering: Water when the top inch of soil feels dry to the touch.
Feeding: It generally does not require extra fertilizer when grown in decent garden soil.
Pruning: Deadhead spent flowers to prevent unwanted self seeding.
Repotting: If growing in a container, move to a larger pot once the roots fill the current space.
Soil: Well drained sandy or loamy soil
Soil pH: 6.0 to 7.5
Temperature: -20 to 30°C
Humidity: 40 to 70%
Drought tolerance: Moderate
Lifespan: Biennial, typically 2 years.
Deer and rabbits: High

Signs it needs repotting

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

Safety

People: The plant contains pyrrolizidine alkaloids that cause liver damage upon ingestion.
Pets: This plant is toxic to cats and dogs if ingested, as it contains pyrrolizidine alkaloids that can cause liver damage.
Children: Keep children away from this plant as ingestion of any part can cause severe poisoning.
Contact allergens: Handling the foliage can cause skin irritation or dermatitis in sensitive individuals.
Airborne allergens: The pollen can trigger allergic reactions in some people during the flowering season.
Edibility: This plant is toxic to humans and livestock if ingested.

How to identify it

Bright yellow daisy like flower heads
Deeply lobed dark green leaves
Sturdy upright stems
Basal rosette of leaves in first year

Height: 0.3 to 1.2m
Spread: 0.2 to 0.5m
Leaves: dark green, deciduous
Flowers: yellow, 1 to 2cm
Fruit: brown, Autumn

Problems to watch for

Powdery MildewCommon
RustCommon
AphidsUncommon
Slugs and SnailsUncommon

By symptom

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Growing it

Propagation: seed
When to plant: spring, autumn
Overwintering: The plant forms a low rosette of leaves during the winter months. No special protection is needed as it is quite hardy.
In containers: Not recommended for containers due to its aggressive seeding habit.

Seed

Collect seeds in late autumn.
Sow directly into disturbed soil.
Keep the area moist until germination.

Plant in areas where you want to support native pollinators, but keep it away from grazing areas.

Grows well with

Common Yarrow · They share similar habitat requirements and support a wide range of pollinators.

Similar species

Golden Ragwort · It shares similar yellow daisy like flowers but is less aggressive.

Science

Family: Asteraceae
Genus: Jacobaea
Order: Asterales
Class: Magnoliopsida
Native range: Europe and western Asia.
Conservation: It is often classified as a noxious weed and is subject to control measures in many regions.

It thrives in open, disturbed ground where it outcompetes native grasses.

Value to wildlife: nectar source, larval host plant
Pollinators: bees, butterflies, moths, beetles
Uses: pollinator garden, 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 it safe to touch?: It is best to wear gloves when handling it to avoid skin irritation.
Does it spread easily?: Yes, it produces thousands of wind dispersed seeds.

Where the name comes from

The name Jacobaea refers to St. James, while vulgaris means common.

Good to know

It is a primary food source for the cinnabar moth caterpillar.
The plant is biennial in its first year and flowers in its second.
It is widely considered an invasive weed in pastures.

Also in

Plants toxic to cats and dogs

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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.