Cook County, IL Landscaping Rules: Native Plants (2026)
Key Facts
- Governing chapter
- Ch. 126, Art. III Landscaping and Screening
- Geographic scope
- Unincorporated Cook County only
- Triggers
- Building permits, PUDs, lots over 20 spaces
- Invasive species
- Listed species explicitly prohibited
- Enforcement
- Commissioner of Building and Zoning
Summary
In unincorporated Cook County, required landscape plans for building permits, PUDs, and large parking lots must use plants from the County's approved native list and may not include specified invasive species.
(d) In addition to the requirements set forth in this section with respect to utilization and maintenance of plant material in landscape plans, plant material utilized to conform with the requirements contained in this section shall be selected from a list of approved native plants... Utilized native plants shall be maintained in proper condition and shall be replaced with similar native plants, as necessary. Native plants are plants that flourish and thrive with little assistance in Cook County... Invasive plants may not be utilized.
Full Breakdown
Cook County's landscaping code (Ch. 126, Art. III) requires that plant material used on a required landscape plan for building permits on principal structures, planned unit developments, special and unique uses, and parking lots over 20 spaces be selected from the County's approved native plant list, drawn from illinoiswildflowers.info. Native plants are defined as species that flourish with little assistance and were growing wild in the area when scientific collection began. A companion table bars specific invasive species such as garlic mustard, purple loosestrife, and Japanese knotweed, and lists native alternatives. Owners must maintain landscaping and replace dead plants within 30 days. It applies only in unincorporated Cook County; Chicago and the County's 130-plus municipalities set their own rules.
Violations & Fines
Failure to use approved native or non-invasive plant material, or to maintain and replace it, is a code violation subject to fines, penalties, and injunctive relief under Appendix A, Article 13.
Frequently Asked Questions
Does this rule apply within Chicago or in suburbs like Evanston?
Which projects trigger the native-plant landscape plan requirement?
What happens if invasive species are planted instead?
Sources & Official References
Other rules in Cook County
Compare Cook County to another location·View the Illinois landscaping rules overview
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