Petaluma, CA Landscaping Rules: Native Plants (2026)

There is no Sonoma County ordinance requiring homeowners to plant native species, and residents are free to choose ornamental, native, or drought-tolerant plants. Where plant choice is effectively regulated is through the County's Water Efficient Landscape Ordinance (WELO), codified at Sonoma County Code Chapter 7D3, adopted December 15, 2009 and effective January 15, 2010. WELO applies to qualifying new and rehabilitated landscapes tied to building, grading, or design-review permits and to homeowner projects with buildings/additions over 400 square feet (with an exemption if landscape area is under 5,000 sq ft, turf is 600 sq ft or less, and a weather-based controller with rain sensor is used). WELO categorizes plants by water use - high (turf, annuals), moderate (ornamental trees, shrubs, groundcovers, perennials), and low (drought-tolerant, drip-irrigated) - and requires the landscape to meet a water budget, which in practice pushes designs toward low-water, climate-appropriate, and often native plantings. Separately, the Russian River-Friendly Landscaping program offers guidelines, plant lists, and recognition for native and watershed-friendly landscaping, but it is a voluntary program, not a mandate. The County's tree ordinances also protect existing native trees once established (see tree-removal topics).