Colusa County, CA Landscaping Rules: Native Plants (2026)

Colusa County promotes native and drought-tolerant landscaping primarily through guidance rather than mandate. The zoning code's General Landscape Guidelines (Section 44-3.10.020, Ord. No. 765) state that plants 'should be selected from a County-approved list of native, water-conserving, and non-invasive species,' and recommend grouping plants into hydrozones by water need and applying at least a two-inch mulch layer on exposed soil. The code defines 'xeriscape landscaping' as landscaping that reduces or eliminates the need for supplemental irrigation water (using rocks, gravel, bark, and similar materials), and Section 44-3.10.040.C expressly allows xeriscape to satisfy minimum landscaped-area requirements in commercial, mixed-use, and industrial zones. These provisions apply to landscape projects subject to Section 44-3.10 (generally new or rehabilitated landscapes of 2,500+ square feet in urban zones). Separately, native and riparian vegetation that protects waterways is protected within the fifty-foot natural resource buffer area under Section 44-5.20, where cutting or altering protective vegetation is restricted. The county also recognizes 'special-status species' and California Native Plant Society-listed rare plants in its zoning definitions. There is no requirement that an ordinary rural homeowner plant natives. Cities of Colusa and Williams follow their own codes.