This species should not be confused with the ornamental St. Johnswort found in gardens. Common St. Johnswort is taller and less dense, with smaller flowers. Usually found along roadsides and in empty lots in western WA, this weedy species can also be found in natural areas. In eastern WA and in other regions of the western US, common St. Johnswort is widespread and difficult to control.

For more information about common St. Johnswort, please follow this link to the WA State Noxious Weed Control Board.