Tanacetum cinerariifolium aka Dalmatian Insect Flower

Tanacetum cinerariifolium belongs to the Asteraceae family. This perennial lives for more than one year. People call it Dalmatian pyrethrum or insect-powder plant. It comes from the western Balkan Peninsula. Its range takes in Albania, Bosnia and Herzegovina. It also includes Croatia and Montenegro. It grows on rocky ground, often near the sea. It forms part of the plant life of temperate climates.

Plants reach about 1.6 feet [0.5 metres] tall and wide. They suit garden beds where water drains well. They bloom from July to September. The small yellow flowers in each disc make pyrethrins. These compounds go into pyrethrum sprays that kill insects. Each flower has both male and female organs. Bees and flies move pollen from flower to flower. Plants can also set seed with their own pollen. Seeds ripen from August to September.

Grow this plant in full sun, not shade. It accepts sand, loam, or clay that drains well. Sources say rich soil full of humus suits it. So does dry, stony ground rich in lime. Soil can range from mildly acid to very alkaline. The reported pH range is 5.2 to 7.5. Soil may be dry or moist, but damp climates pose risks. Plants may die after they bloom if the climate stays moist. They cope with frost and coastal exposure. PFAF lists USDA hardiness zones 5–9.

Growers raise this plant to make products that kill insects. The dried flower buds supply pyrethrum. This also kills helpful insects. Open flowers hold more pyrethrins than flowers at earlier stages. Reports suggest that live plants keep insects off nearby plants. This gives the plant a use beyond garden beds. PFAF reports no risk of it becoming a weed. It lists no known uses as food. Its score for use as food is zero out of five.

This plant can cause strong allergic reactions in some people. Long contact with dried flowers can make skin inflamed. It can also cause nasal allergies and asthma. Reports say pyrethrum has low toxicity to mammals. Those reports do not rule out these allergy risks. PFAF notes limited use as a medicine. Past uses in China include treating worms in the gut. Research found that flowers also have a weak antibiotic effect. Grow plants from seed sown in spring. You can also split plants in spring to grow more. Protect young seedlings through their first winter before planting outside.