Background: A native to southeastern Eurasia, Canada thistle reproduces by seeds and rootstock. It is adaptable to a diverse range of habitats.
Other common names: California thistle, field thistle
Description: Canada thistle is a perennial plant usually from one to four feet tall, in sparse to extremely dense colonies. Leaves have spiny tipped lobes. Flowerheads are softly spined, light pink to purple, and are typically three-quarter inch in diameter. Bloom occurs in July and August.
Control: Several biocontrol agents are available offering fair control. Herbicides can offer good control when applied to actively growing plants from spring to fall. As with most creeping perennials, digging or tillage is generally not effective. Contact your local state or county weed specialist for specific updated infromation.