Joliet, IL Invasive Plant Rules: Prohibited Species (2026)

Joliet's tree ordinance singles out invasive woody plants for the opposite treatment it gives native and planted trees. Sec. 26-128(k)(1) states that 'these species shall not be planted, should be removed, and controlled to reduce impacts to other vegetation,' naming buckthorn as the code's example and pointing to the woody invasive species list kept in the Urban Forest Management Plan for the full roster. The same subsection explains why: invasive plants disrupt soil chemistry, crowd out light needed by other species, and can displace native plants into a monoculture.

That removal encouragement isn't just aspirational, it's backed by a permitting exemption. Sec. 26-128(g)(5) states plainly that 'removal of invasive woody plants such as buckthorn does not require a permit and is encouraged,' cutting through the four-inch DBH permit threshold that applies to every other regulated tree on covered land. The planting side of the rule is enforced through Sec. 26-128(d)(4), which makes it 'unlawful' to plant a species in the right-of-way or on public land that is listed as invasive or undesirable in the management plan, and subsection (h)(6) confirms there's no replacement-tree obligation when an invasive species comes out, since the code doesn't want a buckthorn thicket replaced tree-for-tree. The city arborist maintains the definitive invasive species list and fields questions about which species qualify.