St. Louis County, MO Landscaping Rules: Native Plants (2026)

5, part of the county's landscaping and screening regulations, requires the use of native landscaping for at least one-half of the landscaping on a site subject to the section, and caps any one plant species at no more than 33 percent of the overall landscape plan. The native-plant standard itself, in subsection (2)(a), requires all covered landscape plans to use at least fifty (50) percent native and/or drought-tolerant plant materials as appropriate to their location, with a detailed plant list submitted alongside the plan. The same subsection bans invasive plants, defined by reference to the Missouri Department of Conservation's Missouri Vegetation Manual, and noxious weeds, defined by reference to the Missouri Department of Agriculture's Missouri State Noxious Weed List, from new landscaping altogether.

1 exempts "single-family residential units on platted lots" from the entire section, so a typical homeowner's yard is not held to the 50 percent native-plant threshold; the rule binds site plans for commercial development, multi-family projects, parking lots, and other uses that go through the county's site development plan or conditional use review. 10 requires a two-year bond or escrow whenever estimated landscaping costs exceed $10,000, with 80 percent of the funds released once the Department of Planning confirms installation matches the approved plan, and the remaining 20 percent held for a full year afterward to confirm the plants survive.