San Mateo County, CA Landscaping Rules: Weed Ordinances (2026)

County weed abatement authority derives from Gov Code §39560 et seq. (general nuisance abatement) and Health & Safety Code §14875 (noxious weed seizure). The County's Weed Abatement Program runs annually in parallel with defensible space inspections in SRA/VHFHSZ communities. Vacant lots in hillside neighborhoods (Emerald Hills, Skylonda, Montara, Moss Beach, Pescadero) receive priority attention. Property owners must clear dry grass, dead brush, and weeds taller than 18 inches (6 inches close to structures) before fire season. The San Mateo County Agricultural Commissioner maintains the county's noxious weed list per Food & Agricultural Code §5004 — French broom, Scotch broom, and jubata grass are local priority species for eradication. Notices include a compliance deadline (typically 30 days); after that the County contractor performs abatement and bills the property owner. Unpaid abatement costs become a lien filed against the parcel with the County Recorder. In VHFHSZ defensible-space inspections override the general weed ordinance with the stricter PRC §4291 100-foot requirement.