Antioch, CA Landscaping Rules: Weed Ordinances (2026)

California regulates noxious weeds under Food and Agricultural Code Section 5004, which empowers each County Agricultural Commissioner to enforce the statewide A-rated, B-rated, and C-rated noxious weed lists maintained by the California Department of Food and Agriculture (CDFA). In Antioch and the broader east Contra Costa region, the most frequently cited noxious weeds include yellow starthistle (Centaurea solstitialis, C-rated), artichoke thistle (Cynara cardunculus, B-rated), perennial pepperweed (Lepidium latifolium, B-rated), purple star thistle, and medusahead grass. These species pose fire and rangeland hazards and are particularly problematic on the city's grassland fringes and undeveloped parcels. Under Antioch Municipal Code Chapter 6-3 and parallel county provisions, property owners must control the spread of noxious weeds; this may require mechanical removal, targeted herbicide treatment, or prescribed grazing. The Contra Costa County Agricultural Commissioner can issue compliance agreements and, for unabated infestations, recover control costs from the owner. Intentional cultivation or transport of A-rated species (such as Russian thistle varieties) is prohibited. Homeowners who are uncertain about a plant on their lot may submit samples to the Agricultural Commissioner's Concord office for free identification. Voluntary eradication programs coordinated by the East Bay Regional Park District cover adjacent open-space corridors.