Boulder County, CO Landscaping Rules: Weed Ordinances (2026)
Key Facts
- Height limit
- 9 inches (lots ≤2.5 acres)
- Governing code
- Land Use Code 14-400(G)
- Noxious weeds
- Weed Management Plan / C.R.S. 35-5.5
- Exempt
- Cultivated beds, gardens, food crops
- Applies to
- Unincorporated residential lots
Summary
On residential lots of 2.5 acres or less, brush, shrubs, grasses, and weeds must generally be kept under nine inches. Growth over nine inches that causes a nuisance violates Land Use Code Article 14; designated noxious weeds fall under the county's mandatory Weed Management Plan.
Weeds and Brush: Any underbrush, bush, shrub, or plant material greater than nine inches in height which: ... is allowed to grow in such a manner or extent that it causes or is likely to cause a public hazard or nuisance ... and is not a noxious weed designated under the County's Noxious Weed Management Plan.
Full Breakdown
Article 14 defines regulated 'weeds and brush' as any underbrush, bush, shrub, or plant material greater than nine inches in height that grows without cultivation and is allowed to grow so as to cause a public hazard or nuisance. This applies to residential lots of two and one-half acres or less. Planting beds, cultivated gardens, and food-production plots are excluded, and state-designated noxious weeds are handled under the County Noxious Weed Management Plan (C.R.S. 35-5.5) rather than Article 14. Cities enforce their own grass-height rules within their limits.
Violations & Fines
Written notice with an abatement deadline (ordinarily 30 days). If uncut, the county mows and bills the owner, adding up to a 10% inspection charge; unpaid amounts add a 10% penalty and go to the county treasurer.
Frequently Asked Questions
Does the nine-inch limit apply to my acreage or garden?
What about noxious weeds like thistle?
Sources & Official References
Other rules in Boulder County
How Boulder County compares: Cities with the Strictest Weed and Property Maintenance Rules·Compare Boulder County to another location·View the Colorado landscaping rules overview
See something wrong?
Help us keep this page accurate. If you notice an error or outdated information, let us know.