Common tansy (Tanacetum vulgare) is a weed-like perennial flower that grows from rhizomatous roots and is also known as bitter buttons, cow bitter, and golden buttons. While now considered invasive in North America, at one time the plant was an important culinary herb in Europe. Given its pedigree in the European tradition, it is not surprising that tansy flowers were soon brought to the New World by American colonists and granted a position of garden prominence. From there, however, it soon naturalized into surrounding areas and is now viewed as a noxious weed over large areas of the United States.
The name is derived from the Greek athanatos, meaning immortality, either because it is long-lived or because tansy was used for embalming in ancient times. In Greek mythology, Zeus was said to have made Ganymede immortal by giving the him tansy on Mount Olympus. Now, however, tansy has been listed by watchdog groups as one of the worst invasive plants in North America.
Tansy can be identified by its aromatic, fern-like foliage, and bright yellow button-like flowers that appear in flat-topped clusters in summer. The leaves bear a similarity to yarrow, which is also a member of the Asteraceae family of plants.
|Botanical Name||Tanacetum vulgare|
|Common Names||Common tansy, bitter buttons, cow bitter, golden buttons|
|Plant Type||Herbaceous perennial flowering plant|
|Mature Size||2 to 4 feet tall, 12- to 18-inch spread|
|Sun Exposure||Full sun to part shade|
|Soil Type||Well-drained, fertile soil|
|Soil pH||4.8 to 7.5|
|Bloom Time||July and August|
|Hardiness Zones||3 to 8 (USDA)|
|Native Area||Temperate regions of Europe and Asia, naturalized over much of North America|
|Toxicity||Toxic to humans, dogs, cats, and livestock.|
How to Care for Common Tansy
Common tansy is a low-maintenance plant that requires very little care on the part of the gardener. Although it is considered an invasive plant, it does have its uses. When properly harvested and dried, the bright yellow button flowers produce a soft yellow dye. The plant's history as a strewing herb still bears out today as Common Tansy will repel flies and other pesky insects. Additionally, tansy flowers add potassium to soil and attract an important beneficial insect, the ladybug.
If you're considering growing tansy flowers, make sure to clip off the spent flowers to prevent this troublesome plant from self-seeding. Keep in mind that it's prohibited in Colorado, Minnesota, Montana, Wyoming, parts of Washington state, and the Alberta and British Columbia provinces in Canada.
Tansy flowers grow best in full sun, though they can tolerate part shade.
This perennial plant prefers well-drained, fertile garden soil but tolerate almost any soil conditions.
Tansy can tolerate drought and does not need regular watering.
Temperature and Humidity
Tansy flowers are winter hardy to minus-40 degrees Fahrenheit. The leaves will turn brown, curl, and dry up in extreme prolonged heat.
Pruning Common Tansy
One of the best methods for keeping tansy under control is deadheading the flowers. Cut the foliage and flower stems to the ground every year to keep growth in check. Tansy roots go deep so be prepared to do some heavy shovel lifting if you want to remove the plant completely. You can also try spot spraying with a broad spectrum weed killer. Always use caution, and wear protective clothing, gloves and goggles, when using chemical herbicides.
Common Tansy vs. Tansy Ragwort
Do not confuse this plant with "tansy ragwort" (Senecio jacobea), which is a different plant altogether. Tansy ragwort is a winter annual, biennial or short-lived perennial that is also considered a noxious weed.
Common Pests and Plant Diseases
Since the heavily scented leaves of common tansy act as insect repellent, the plant is not vulnerable to pests or disease. Unfortunately, unless measures are undertaken to control its spread, the plant itself could turn out to be the biggest problem.
Tanacetum vulgare. North Carolina State Extension.
Tanacetum Vulgare. Missouri Botanical Garden
State Noxious-Weed Seed Requirements Recognized in the Administration of the Federal Seed Act. United States Department of Agriculture
Tansy. Cornell University