O'Fallon, MO Landscaping Rules: Tree Removal & Heritage Trees (2026)

O'Fallon Code Chapter 402, Article III governs tree preservation on real property citywide, but § 402-030 exempts any parcel used exclusively for a single-family or two-family dwelling from the whole Article. For everything else, covering agricultural, commercial, industrial, office, and multi-family property, § 402-040 sets two thresholds. Before development, destroying more than 25% of the trees on a parcel is prohibited outright, though land that must be graded or filled to become buildable can get a two-year exemption tied to the grading permit, after which removed trees must be replaced at 15 trees per acre and the disturbed area seeded or sodded to City standards.

Once a site plan or preliminary plat application is submitted, the retention rule tightens: a minimum of 20% of the existing trees, or 15 trees per acre of the whole development, whichever is greater, must be kept standing. Retained trees count toward the project's separate landscaping requirements. Any trees that cannot be retained must be replaced with trees of like or similar kind, at least 4 inches in caliper and 8 feet tall, of a hardwood variety consistent with the Chapter's species list, and the replacements must be maintained to ensure survival for at least 18 months from planting. During construction, § 402-040(C) requires protective barriers around all retained trees and their drip lines to prevent damage. Section 402-060 further requires any site plan for a non-exempt parcel to show the tree protection zone and the location, type, and size of every tree to be maintained within it. Section 402-070 allows the City to waive these requirements during emergencies such as wind or ice storms so cleanup and repair work is not delayed. Authority to approve the landscape plan implementing these standards rests with City staff under § 402-150, subject to added conditions the Planning and Zoning Commission or City Council may impose.