Soil
Well drained fertile soil.
Position
Full sun to light shade.
Frost tolerant
This hardy perennial is winter hardy to -40F (-40C).
Feeding
None generally needed.
Companions
Cabbage.
Spacing
Single Plants: 1′ 5″ (45cm) each way (minimum)
Rows: 1′ 3″ (40cm) with 2′ 11″ (90cm) row gap (minimum)
Sow and Plant
Start with a purchased plant, or sow tansy from seed. These vigorous plants spread and reseed, so it is best to start with only one plant, and grow it as a managed clump. Locate in a spot where you can mow around the clump to further manage its spread.
Notes
Tansy is an eager spreader wherever it is grown, but it is such an aggressive reseeder in some climates that it is listed as a noxious weed. Growing tansy is prohibited in Colorado, Minnesota, Montana, Wyoming, and parts of the state of Washington, as well as the Alberta and British Columbia provinces in Canada.
Harvesting
Harvest leaves when needed, and expect flower clusters in late summer. Cut back plants close to the ground in early spring.
Troubleshooting
Tansy leaves can cause contact dermatitis in sensitive people, and the plants are poisonous to some animals when eaten.