Thornton's Landscaping Rules: The Rules That Matter

Every city handles landscaping rules a little differently. In Thornton, Colorado, there are 5 distinct rules that residents and property owners should be aware of. Some are stricter than what neighboring cities enforce, and others are more relaxed. Here is what you need to know.

Water Restrictions

From April 1 through October 31, Thornton limits turf watering to three days a week chosen by the customer, with no irrigation between 10 a.m. and 6 p.m. New sod and seed get temporary exceptions, and large turf areas like parks and golf courses can water as needed if best practices are followed.

Key details: Watering days: Up to 3 days per week, customer's choice. Restricted hours: No watering 10 a.m. to 6 p.m.. Season: April 1 through October 31. New sod/seed grace period: 21 days sod, 28 days seed. 1st violation fine (residential): $100, rising to $400 in Drought Stage 3.

Violating the watering schedule triggers the penalty schedule in Section 74-60(d)(2): a first violation costs $100 for single-family, duplex, and individually metered multifamily accounts (rising to $200 or $400 if a drought stage is also in effect), and $250 for commercial, multifamily master-metered, or irrigation accounts. Second and third violations climb to $250-$2,000 and $500-$3,000 respectively depending on account type and drought stage.

Weed Ordinances

Thornton bars property owners and lessees from letting weeds and brush grow past eight inches, with limited exceptions for large lots and specific zoning districts. Owners get 10 calendar days after written notice to cut, or the city can enter, clear the property, and bill the cost under § 38-444.

Key details: Height limit: 8 inches for weeds and brush. Correction window: 10 calendar days after notice. Large-lot exception: Lots over 5 acres, 100-ft buffer. Noxious weeds: Always capped at 8 inches, no exceptions. Nonpayment: Becomes a continuing lien on the property.

Failure to cut weeds or brush below eight inches within 10 calendar days of written notice lets the city perform the work itself and record a lien-backed assessment against the property under §§ 38-444(c) and 38-453. The property owner has 30 days from the assessment notice to pay before it is recorded as a continuing lien, and can object in writing to the municipal court within that same 30-day window to get a hearing.

Tree Trimming

Thornton adopted Model Traffic Code Section 114 as local law through Section 38-523: property owners must trim or remove, at their own expense, any tree limb, shrub, vine, or hedge that projects over the public right-of-way and blocks a driver's view, hides a traffic sign, or otherwise creates a hazard for drivers or pedestrians.

Key details: Governing section: Thornton City Code § 38-523 (MTC § 114). Who must trim: Owner of property abutting the right-of-way. Notice-to-cure period: 10 days after written city notice. City self-help: City may trim and bill owner for cost. Maximum penalty: $1,000 fine, § 1-8(a).

Failing or refusing to remove a tree limb, shrub, vine, or hedge that obstructs the view of traffic or a traffic control device is itself declared unlawful, and any violation of Section 114 is subject to the penalty in Section 1-8(a): a fine of up to $1,000.00. Separately, if the city performs the trimming after a 10-day notice period lapses, the property owner must reimburse the city for the actual cost of that work.

Native Plants

Thornton may encourage or require native and drought-tolerant landscaping. Some areas restrict traditional grass lawns in favor of water-efficient alternatives.

Thornton is more permissive than most cities when it comes to native plants. That said, there are still limits.

Tree Removal & Heritage Trees

Thornton does not require a homeowner permit to remove a healthy tree, but the city forester can order removal of any tree or plant, public or private, that spreads disease or insects or threatens public health and safety, and can bill the owner if they refuse.

Key details: Governing authority: City forester, § 46-102. Compliance deadline: Up to 30 days from notice. Appeal window: 7 days to city manager. Hearing deadline: Within 15 days of appeal. Cost recovery: Unpaid cost becomes a lien.

Failing to comply with a city forester's notice to correct within 30 days (or an extended deadline) is unlawful under Section 46-103(b) and is punishable under the general penalty provision, Section 1-8(a), per Section 46-101. The forester may also perform the removal and charge the owner, with unpaid costs becoming a property lien after 30 days.

The Bottom Line

Thornton's landscaping rules rules are a mixed bag. Some areas are strict, others are relaxed, and the details matter. The best approach is to check the specific rule that applies to your situation rather than assuming Thornton is broadly strict or permissive.

All of the above reflects Thornton's municipal code as of our last review. If you need specifics on fines, exemptions, or filing requirements, the detailed ordinance pages linked above have the full breakdown.