Sonoma County, CA Landscaping Rules: Grass Height Limits (2026)

Sonoma County does not enforce a cosmetic lawn-height limit for unincorporated properties the way some cities do. The measurable grass-cutting requirements come from the County's fire-safety program under Sonoma County Code Chapter 13A (Abatement of Hazardous Vegetation and Combustible Material, Ordinance 6148), administered by Permit Sonoma's Fire Prevention Division. Per the County's published Vegetation Management Requirements for improved parcels in the Local Responsibility Area, owners must 'cut grasses to 6 inches or less' within the lean-clean-and-green zone (0-30 feet from buildings) and 'trim grasses to four inches (4 inches) or less, but not to the bare soil' within 10 feet of roadway frontage. In the State Responsibility Area, a 4-inch maximum grass height applies in both the 0-30 foot and 30-100 foot zones. These requirements are seasonal and tied to fire season, not a year-round aesthetic standard. Annual defensible-space inspections (roughly 4,000+ per year) typically begin in late spring or early summer. So while there is no blanket 'tall grass' nuisance height for a back lawn, dead or dry annual grasses near structures and roads must be kept short during fire season.