Many growers make no distinction at all between perennial and annual sow thistles. That’s because all three versions are tall weeds with yellow, dandelion-like flowers and stems that produce a milky sap. Seedlings of the two species(Sonchus asper & Sonchus oleraceus) are practically indistinguishable, and may be difficult to tell apart even at spray stage without examining the root system. Annual and perennial sow thistle will be covered in an upcoming post.

Spiny Sow Thistle (Sonchus asper):

An annual that has bluish-green leaves and stems that emit a milky sap when cut. Spiny sowthistle is primarily a weed of pastures, hay fields, landscapes and roadsides.  It is found throughout the United States. Young leaves form a basal rosette have a whitish coating.

Basal Rosette of Spiny Sow Thistle

The leaves have very prickly margins that initially develop as a basal rosette and then occur alternately along the flowering stem, the bluish-green color of the leaves, and the yellow flowers with a ‘puff-ball’ seedhead are all characteristics that help in the identification of spiny sowthistle. Spiny sow thistle has a taproot.

Mature Spiny Sow Thistle with Yellow Flowers

Leaves of Spiny Sow Thistle

Select Herbicide Options:

Weedmaster

2, 4-D

GrazonNext HL

Grazon P+D

Milestone

Chaparral (for bermudagrass pastures, will destroy bahiagrass)

Cimarron Max (for bermudagrass pastures, will destroy bahiagrass)

Pastora (for bermudagrass pastures, will destroy bahiagrass)

REMEMBER: THE LABEL IS THE LAW!  Always read the pesticide label before using.