9 county-level rules, plus city-specific rules for 4 cities in San Mateo County, California.
Verified from official government sources
Unincorporated San Mateo County has no general residential lawn-height limit. Grass height is regulated only through wildfire defensible space: in State Responsibility Areas (CAL FIRE) and high fire hazard zones, annual grass must be mowed to a maximum height of 4 inches as part of the 100-foot clearance required by California Public Resources Code 4291.
In unincorporated San Mateo County, pruning a Protected Tree generally does not need a permit, but a Protected Tree Pruning Permit is required to prune a Protected Indigenous Tree where the cut removes a branch or trunk 6 inches in diameter (19 inches circumference) or larger. Trees in the County right-of-way are trimmed by Public Works for safety only.
Cal. Public Resources Code Sec. 4291 (Vegetation Clearance Around Structures)
4291. (a) A person who owns, leases, controls, operates, or maintains a building or structure in the state responsibility area shall at all times do all of the following: (1) (A) Maintain defensible space of 100 feet from each side and from the front and rear of the structure, but not beyond the property line, except as provided in subparagraph (B). The amount of fuel modification necessary sha...
Unincorporated San Mateo County requires a Protected Tree Removal Permit before removing a protected tree. Any tree 12.1 inches in diameter (38 inches circumference) or larger is protected, and listed indigenous species (oaks, madrone, buckeye) are protected at lower diameters. Removal requires replacement planting per Table 2 of Ordinance 8.400.
Unincorporated San Mateo County abates hazardous fire vegetation through its fire districts under California Health & Safety Code 14875 et seq. and Government Code 25845. Programs such as Coastside Fire's require mowing weeds and grass to no taller than 4 inches; lots of one acre or less are cleared entirely, and larger lots need a 30-foot perimeter fire break.
Cal. Food & Agricultural Code Sec. 5004 (Noxious Weed - Definition)
5004. “Noxious weed” means any species of plant that is, or is liable to be, troublesome, aggressive, intrusive, detrimental, or destructive to agriculture, silviculture, or important native species, and difficult to control or eradicate, which the director, by regulation, designates to be a noxious weed. In determining whether or not a species shall be designated a noxious weed for the purpose...
Unincorporated San Mateo County enforces a Water Efficient Landscape Ordinance (WELO) implementing California's Model WELO. It applies to new landscapes of 500 sq ft or more and rehabilitated landscapes of 2,500 sq ft or more, capping turf, requiring low-water (WUCOLS 0.3) plants, 3 inches of mulch, and compost in the soil.
Residential rainwater harvesting is encouraged in unincorporated San Mateo County. Under California's Rainwater Capture Act, rooftop rain barrels and cisterns under 360 gallons for outdoor non-potable use need no state water permit. The Countywide Water Pollution Prevention Program offers rebates of $50-$150 per rain barrel, plus a possible $50 bonus in some areas.
Unincorporated San Mateo County encourages native and drought-tolerant landscaping rather than mandating it for homeowners. The Countywide Water Pollution Prevention Program promotes natives for pollinators and watershed health, and BAWSCA's Lawn Be Gone rebate pays up to $4 per square foot to replace lawn with low-water plants. WELO indirectly favors natives through plant-factor rules.
California Model Water Efficient Landscape Ordinance (MWELO)
About 40% of the water Californians use at home is used outdoors. Large water savings can be gained by efficient landscape design, installation, management, and maintenance. This is accomplished by choosing climate adapted plants, improving soil conditions, using, and maintaining high efficiency irrigation equipment and managing the irrigation schedule to fit the plants water needs as they are ...
Unincorporated San Mateo County does not ban or specifically permit-regulate artificial turf on private property, and the County's WELO governs water budgets without mandating or prohibiting synthetic turf. A right-of-way permit is needed only if turf extends into the public parkway. California law (Civil Code 4735) bars HOAs from prohibiting water-efficient landscaping.
California Civil Code § 4735
4735. (a) Notwithstanding any other law, a provision of the governing documents or architectural or landscaping guidelines or policies shall be void and unenforceable if it does any of the following: (1) Prohibits, or includes conditions that have the effect of prohibiting, the use of low water-using plants as a group or as a replacement of existing turf. (2) Prohibits, or includes conditions t...
California's SB 1383 organics law requires unincorporated San Mateo County residents to keep food scraps, yard trimmings, and food-soiled paper out of the trash. Single-family homes get curbside organics (green cart) service and must sort organics into it. The County aims to cut organic-waste disposal 75% by 2025; non-compliance can lead to fines.
4 cities in San Mateo County have their own landscaping rules rules. Each link goes to that city's dedicated page with code citations.
8 verified rules • Artificial Turf, Grass Height Limits
8 verified rules • Artificial Turf, Grass Height Limits
4 verified rules • Grass Height Limits, Tree Removal & Heritage Trees
4 verified rules • Grass Height Limits, Tree Removal & Heritage Trees
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