Snohomish County, WA Landscaping Rules: Native Plants (2026)

016(3): 30 percent for subdivisions of 10 or more single-family lots, 25 percent for short subdivisions of 4 to 9 lots, 20 percent for short subdivisions under 4 lots and for single-family, cottage, townhouse or multifamily projects of 10 or more units, 15 percent for the same housing types under 10 units, and 15 percent for Urban Center and Mixed Use Corridor residential or mixed-use projects. Subsection (6) governs the species mix planted to meet that canopy: sites must plant or replant at least 50 percent evergreen species, no more than 30 percent of trees from a single species, and no more than 60 percent from a single taxonomic family.

5 percent when the deciduous share of the mix is exclusively species indigenous to the Puget Sound region, excluding alder, and sites meeting their whole canopy requirement through street trees alone are exempt from the evergreen mix entirely. 015(6) backs this up for all required landscaping generally, requiring plant material to meet nursery stock standards published by the American Nursery and Landscape Association and consist of native species drawn from a list the planning director maintains, with substitutions allowed by director approval. 016(5) credits individually retained significant trees at 125 percent of actual canopy area, clustered stands of five or more at 150 to 200 percent, and trees within 20 feet of a rain garden or bioswale at 150 percent, all reducing how much new planting a project needs. 016 entirely. 85 SCC.