Common tansy is native across temperate Eurasia and has been widely introduced in North and South America and Australia. It grows in subalpine river valleys. It is listed as an invasive and noxious weed in several US states, overtaking ditches and disturbed areas.

The leaves of common tansy are highly toxic because they contain thujone. Common tansy is toxic to cats and dogs, causing symptoms like vomiting, diarrhea, and convulsions upon ingestion. The toxin can also be absorbed through the skin. Immediate veterinary care is crucial if a pet is suspected to have ingested common tansy.

Common tansy originates from temperate regions of Europe and Asia. This plant is considered a weed due to its extremely aggressive growth pattern and capability to take over large areas. Its ability to multiply rapidly stems from its prolific seed production and underground rhizomes, which enable it to spread swiftly. Common tansy is harmful because it contains substances that deter beneficial insects, disrupt the balance of soil nutrients, and can even pose health risks to humans and animals if consumed in large amounts. If you grow common tansy in your garden, you should look out for its dense, button-like, yellow flowers and finely-divided, fern-like leaves. The primary means of its dispersion is seed wind dispersion, but it also spreads through the creeping of its rhizomes.

To manage common tansy, it is pivotal to take action before it sets seed, meaning late spring to early summer is often the ideal season for intervention.