Tansy Ragwort

Senecio jacobaea

Family: Asteraceae (ass-ter-AY-see-ee) (Info)
Genus: Senecio (sen-ek-ee-o ) (Info)
Species: jacobaea (jak-koh-BAY-ee-uh) (Info)




Foliage Color:

Unknown - Tell us

Bloom Characteristics:

Unknown - Tell us

Water Requirements:

Unknown - Tell us

Where to Grow:

Unknown - Tell us


6-12 in. (15-30 cm)

12-18 in. (30-45 cm)

18-24 in. (45-60 cm)

24-36 in. (60-90 cm)

36-48 in. (90-120 cm)

4-6 ft. (1.2-1.8 m)


9-12 in. (22-30 cm)


USDA Zone 8b: to -9.4 C (15 F)

USDA Zone 9a: to -6.6 C (20 F)

USDA Zone 9b: to -3.8 C (25 F)

USDA Zone 10a: to -1.1 C (30 F)

USDA Zone 10b: to 1.7 C (35 F)

USDA Zone 11: above 4.5 C (40 F)

Sun Exposure:

Full Sun

Sun to Partial Shade

Light Shade

Partial to Full Shade


All parts of plant are poisonous if ingested

Bloom Color:

Bright Yellow

Bloom Time:

Late Spring/Early Summer

Mid Summer

Late Summer/Early Fall

Mid Fall

Late Fall/Early Winter


Unknown - Tell us

Other details:

May be a noxious weed or invasive

Soil pH requirements:

6.1 to 6.5 (mildly acidic)

6.6 to 7.5 (neutral)

7.6 to 7.8 (mildly alkaline)

Patent Information:


Propagation Methods:

From seed; direct sow outdoors in fall

By stooling or mound layering

Seed Collecting:

Unknown - Tell us


This plant has been said to grow in the following regions:

Salem, Oregon

Friday Harbor, Washington

Issaquah, Washington

Gardeners' Notes:


On Jul 13, 2011, DMersh from Perth
United Kingdom (Zone 7b) wrote:

Native to Europe, known as common ragwort there. Produces huge numbers of seeds carried by air, can be a very rampant invader of waste ground, meadows etc having the ability to almost completely take over large tracts of land. thrives on various soil types including dry areas with poor soil. A bit sporadic in where it occurs though, being dependent on the wind to disperse seeds.
Poisonous to horses and cattle, less so to sheep which may eat it.
A favourite food of the Cinnabar moth.
The term 'tansy ragwort' is incorrect and causes confusion, Tansy is a separate species entirely though there is a slight resemblance between the two species, both having bright yellow flowers. 'Ragwort' or 'common Ragwort' is the proper name for this species.


On Jul 20, 2008, bonitin from Gent
Belgium (Zone 8a) wrote:

I want to say something in the defense of this beautiful wildflower. In the right place it is a very valuable plant, a very rich nectar source for hoverflies, bees, butterflies, moths etc..


On Feb 8, 2005, Todd_Boland from St. John's, NL (Zone 5b) wrote:

It is a noxious weed but it is a great plant for butterflies and bees. If you have a wildflower garden, then I would not be against growing this plant. Cut the heads off as soon as the flowers have passed and you will prevent their self-seeding everywhere. This plant only reproduced by seed, not by rhizomes.


On Nov 25, 2004, caron from Woodland Park, CO (Zone 4b) wrote:

Colorado Class A Noxious Weed. Mandatory eradication.
All locations of this plant in Colorado should be immediately reported to the Colorado Department of Agriculture.


On Sep 5, 2004, spur from Florence, OR wrote:

Out here on the Oregon Coast tansy is extremly invasive, the forest service has released a moth of some kind that eats it to help control it. It is very poisonous to horses, and the symptoms may not show up for years, I believe it eats away at their liver and kidneys. It's flowers aren't worth the pain to keep it in check, and to keep the animals away from it.


On Dec 30, 2002, DerekSmith wrote:

Highly poisonous. Invasive in untilled soils. Designated by many governments as injurious weed and controlled by legislation. Can cause extensive losses to cattle an horse farming. Can cause death to humans by ingestion or skin absorption leading to liver failure, cirrhosis or cancer.
Contains many Pyrrolyzadine Alkaloids