Poa Annua – Annual Bluegrass
February 5, 2016
February 5, 2016

Bull thistle (Cirsium vulgare) is a noxious weed that can take root just about anywhere. The tall, flowering weed has the ability to completely overtake other plants, and can significantly reduce hay production as well as the production of other agriculture. With stalks growing upwards of seven feet tall, the purple flowers can often crowd out any other competing plant life in an area where it has taken hold.


Bull thistle is a biennial weed, which means it flowers every two years. It has a large, single upright stem which grows between three and seven feet tall. In the first year, it begins by growing a rosette, which is a cluster of leaves at the base of the plant, and it blooms in the second year. Blooms are typically purple, though they can sometimes be white. The flowers are between 1-2 inches in diameter and are spike-tipped and usually bloom between July and September.

Dew Covered Dragonfly and Bull Thistle

Where is Bull Thistle Most Likely to Be Found?

The noxious weed is typically found in areas of disturbed ground. This includes pastures, hay fields, roadsides, and ditches along highways and byways. The rugged, exposed clumps of ground provide ample opportunity for the weed to make contact and take root with soil.

Eradicating the Weed

Pulling from the roots and disposing of the weed when it is not flowering, and eliminating the spread of seeds is extremely effective. It may also be mowed, though this is likely to spread seeds. Herbicidal elimination from a weed control expert or lawn care service is probably the best way of eliminating the weed from lawns, pastures, and grassy areas.

Bull thistle is a hearty weed that can take root in a number of locations and crowd out healthy plants. Recognizing it and eliminating it immediately are the best ways of mitigating the weed early on to prevent the spread and takeover of the plant.