Twain Harte, CA Landscaping Rules: Native Plants (2026)

Tuolumne County does not dictate what an individual homeowner may plant in an ordinary yard, but for development projects subject to its Water Efficient Landscape Ordinance (Chapter 15.28, Ord. 3293, 2015) it sets clear native-and-drought-tolerant standards in Section 15.28.040. Subsection (A) requires that only drought-tolerant vegetation species be planted for ornamental purposes, that such plants be listed in the County's Landscape Guidelines and rated as having low or very-low water need, and that the use of invasive or noxious plant species be prohibited. Subsection (B) requires that native or existing vegetation be retained on the project site to the maximum extent feasible. The ordinance also directs designers to reflect plants' horticultural attributes (mature size, invasive roots) to avoid damage to buildings, sidewalks, and power lines, keeping mature vegetation at least 10 feet from power lines; to use solar orientation for summer shade and winter solar gain; and to avoid fire-prone plant materials and highly flammable mulches. These standards apply to public-agency, commercial, industrial, and multifamily projects subject to a discretionary or building permit, and to certain single-family subdivision and planned-development landscaping; agricultural uses and several other categories are exempt under Section 15.28.020. So while there is no mandate that homeowners replace lawns with natives, the County's covered-project rules strongly favor native, climate-adapted, drought-tolerant planting and ban invasive species.