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Adams County, CO Landscaping Rules: Weed Ordinances (2026)

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

Key Facts

Weed height limit
6 inches for grasses and plant growth
Noxious weeds
Prohibited outright, no height threshold
Exempt
Cultivated flowers, gardens, trees and shrubs
Governing ordinance
Ordinance No. 12, effective July 1, 2026
Maximum fine
$1,000 per violation, per day

Summary

Unincorporated Adams County caps weeds and uncultivated plant growth at 6 inches under Section 302.4 of its Property Maintenance Code, adopted through Ordinance No. 12. Noxious weeds are banned outright regardless of height, and the limit exempts cultivated flowers and gardens along with trees and shrubs.

City-specific rules exist: Thornton, and Westminster have their own weed ordinances rules that differ from Adams County's county-level regulations. If you live in one of those cities, check the city-specific page instead.

302.4 Weeds. Premises and exterior property shall be maintained free from weeds or plant growth in excess of 6 inches. Noxious weeds shall be prohibited. Weeds shall be defined as all grasses, annual plants and vegetation, other than trees or shrubs provided; however, this term shall not include cultivated flowers and gardens.

Full Breakdown

4 of the Property Maintenance Code of Adams County, part of the 2024 International Property Maintenance Code amendments adopted under Ordinance No. 12 (effective July 1, 2026), requires that premises and exterior property be maintained free from weeds or plant growth in excess of 6 inches, and separately provides that noxious weeds shall be prohibited with no height threshold at all. The section defines a weed broadly as all grasses, annual plants and vegetation, other than trees or shrubs, but it specifically carves out cultivated flowers and gardens from that definition, so a maintained flower bed or vegetable garden is not measured against the 6-inch limit.

The rule applies to both vacant and occupied improved property in unincorporated Adams County, since the section refers to premises and exterior property generally rather than singling out vacant lots. This replaces the county's prior reliance on the state noxious-weed statute alone: Adams County's own code now sets a specific, enforceable inch-count for ordinary grass and weed growth rather than leaving the standard to state noxious-weed classifications, which only address a defined list of invasive species and never set a general mowing height.

Violations & Fines

A property that exceeds the 6-inch limit or harbors noxious weeds is subject to Ordinance No. 12's general violations clause: a fine of up to $1,000 per separate violation under C.R.S. § 30-28-409, with each day the overgrowth continues counted as a separate offense until the property is mowed or cleared.

Frequently Asked Questions

How tall can my grass legally get in unincorporated Adams County?
No more than 6 inches under Section 302.4 of the county's Property Maintenance Code. Anything taller is a maintenance violation, and noxious weeds are prohibited at any height regardless of the 6-inch general limit.
Does the 6-inch weed limit apply to my vegetable garden?
No. Section 302.4 specifically excludes cultivated flowers and gardens from its definition of a weed, along with trees and shrubs, so a maintained garden bed is not measured against the 6-inch height limit even if some plants in it grow taller.
What's the fine for letting weeds grow too tall?
Up to $1,000 for each separate violation under C.R.S. § 30-28-409, the penalty that applies to every violation of Ordinance No. 12, including the Property Maintenance Code's weed height limit. Each day the overgrowth continues can count as its own separate offense.

Sources & Official References

Other rules in Adams County

All Adams County rules

How Adams County compares: Cities with the Strictest Weed and Property Maintenance Rules·Compare Adams County to another location·View the Colorado landscaping rules overview

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