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St. Clair County, IL Landscaping Rules: Weed Ordinances (2026)

Some Restrictions
Compiled from the official code textEditor Martyn O'NeillLast verified September 2026

Key Facts

County height trigger
Over 8 inches
Named weeds
Ragweed, thistle, poison ivy, Johnson grass
State law
Illinois Noxious Weed Law 505 ILCS 100
Control Authority
The county
Owner duty
Control and eradicate listed weeds

Summary

St. Clair County Code Chapter 25 names specific weeds (ragweed, thistle, poison ivy, Johnson grass and others) and declares them a nuisance on unincorporated residential lots once over eight inches. Illinois' Noxious Weed Law adds a statewide duty to control listed noxious weeds.

These county ordinances apply to unincorporated areas of St. Clair County. Incorporated cities within the county may have their own rules that take precedence over county-level regulations.

"Weeds" as used in this Code shall include, but not be limited to the following: Burdock, Ragweed (giant), Ragweed (Common), Thistle, Cocklebur, Jimson, Blue Vervain, Common Milk Weed, Wild Carrot, Poison Ivy, Wild Mustard ... and Johnson Grass and all other grass or noxious weeds.

View official code

Full Breakdown

Section 25-1-1 defines regulated weeds to include burdock, giant and common ragweed, thistle, cocklebur, jimson, poison ivy, wild hemp, Johnson grass and all other grass or noxious weeds. Once over eight inches on an unincorporated residential subdivision lot they are a declared nuisance (25-1-2), cured within 10 days of notice or abated by the county at the owner's cost with a lien (25-1-5, 25-1-6). Separately, the Illinois Noxious Weed Law (505 ILCS 100) makes each county the 'Control Authority' and requires every landowner to control and eradicate state-listed noxious weeds such as musk and Canada thistle, kudzu and Johnson grass.

Violations & Fines

County: abatement cost plus a superior lien and a Chapter 1 fine. State: under 505 ILCS 100 the Control Authority may enter and eradicate, charging the cost to the owner as a lien if unpaid within six months.

Frequently Asked Questions

Which weeds must I control by law?
The county lists ragweed, thistle, poison ivy, Johnson grass and more; Illinois' Noxious Weed Law adds musk and Canada thistle, kudzu, giant ragweed and Johnson grass statewide. Landowners must control and eradicate them.
Can the county come cut my weeds?
Yes. If you don't abate within 10 days of notice, the county may cut the weeds and charge you, recording a lien superior to all liens except tax liens.

Sources & Official References

Other rules in St. Clair County

Fence Regulations: Height LimitsSome RestrictionsCompostingSome RestrictionsNoise Ordinances: Aircraft NoiseSome RestrictionsParking Rules: Driveway RulesSome RestrictionsFence Regulations: Material RestrictionsSignificant RestrictionsFence Regulations: Retaining WallsSome RestrictionsFence Regulations: Fence Permit RequirementsSome Restrictions

All St. Clair County rules

How St. Clair County compares: Cities with the Strictest Weed and Property Maintenance Rules·Compare St. Clair County to another location·View the Illinois landscaping rules overview

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