Yellowstone County, MT Invasive Plant Rules: Prohibited Species (2026)

Yellowstone County has no list of individually banned plant species in its Zoning Code, but it does bar invasive growth habits from required landscaping in unincorporated Yellowstone County. 1, governing Landscape Plan Preparation, requires that plant materials used to meet the article's landscaping requirements have noninvasive growth habits, alongside being appropriate to planting conditions, encouraging low-maintenance design, and being otherwise consistent with the article's intent. The Zoning Code's definitions article separately defines Invasive Species as an alien, non-naturalized species whose introduction does or is likely to cause economic or environmental harm or harm to human health and which tends to disrupt natural ecosystems by displacing naturalized species, the backdrop against which the noninvasive-growth-habit requirement operates.

4(a) states that the use of non-naturalized, high water consumptive turf or other monoculture seeding is discouraged. Because the requirement is written into landscape-plan preparation, it applies whenever Article 27-1200 requires a landscape plan, which Section 27-1202 triggers for new development, street-frontage landscaping, bufferyards, parking-lot landscaping, and tree preservation, and it is checked by the zoning coordinator before a zoning compliance permit issues.