How Ontario Handles Landscaping Rules: A Practical Guide

Ontario maintains 118 local ordinances across all categories, and 8 of those deal specifically with landscaping rules. Here is a breakdown of what the city actually requires, what is prohibited, and where Ontario falls on the strict-to-permissive spectrum compared to other cities.

Rainwater Harvesting

California's Rainwater Capture Act (AB 1750) lets Ontario residents collect roof rainwater for outdoor use without a permit for simple barrels. Large cisterns and indoor use require plumbing permits.

Key details: State law: Rainwater Capture Act (AB 1750). Small barrels: Generally no permit. Large cisterns: Plumbing permit required. Indoor use: Permit and backflow device. Mosquito control: Screen all openings.

Unpermitted pressurized or indoor rainwater systems can trigger a stop work order and required correction. Mosquito breeding violations are cited by San Bernardino County Mosquito and Vector Control rather than the city.

Ontario is more permissive than most cities when it comes to rainwater harvesting. That said, there are still limits.

Artificial Turf

Ontario allows artificial turf at homes subject to drainage and zoning rules. Civil Code 4735 (AB 349) blocks HOA bans, and AB 1572 makes synthetic turf a compliant replacement for commercial non-functional turf.

Key details: City status: Allowed with drainage and zoning check. HOA protection: Civil Code 4735 (AB 349). AB 1572 alternative: Qualifies to replace non-functional turf. Permit: Usually none for at-grade residential. Front yard: Subject to planted-area minimums.

Improper drainage that causes water to discharge onto neighboring property or the public right of way can be cited as a nuisance. Installations that exceed front-yard paving caps or violate zoning setbacks require correction under a Code Enforcement notice.

Ontario is more permissive than most cities when it comes to artificial turf. That said, there are still limits.

Native Plants

Ontario enforces the state Model Water Efficient Landscape Ordinance (MWELO). New residential landscapes over 500 sq ft must meet water-budget, plant, and irrigation rules favoring natives and low-water species.

Key details: State rule: MWELO 23 CCR 490 et seq.. Residential threshold: Over 500 sq ft triggers review. Commercial threshold: Over 2,500 sq ft triggers review. AB 1572: Ends turf at commercial sites 2027. HOA override: Civil Code 4735 protects natives.

Landscape plans that fail MWELO review are rejected at permit. Existing non-conforming landscapes installed without required permits can be cited and required to retrofit to current standards as a condition of certificate of occupancy.

Weed Ordinances

Ontario Municipal Code Chapter 6-9 (Weeds and Refuse Abatement) declares it unlawful and a public nuisance for any property to allow weeds, rubbish, refuse, or dirt to exist on it (Sec. 6-9.02). The City defines weeds to include brush that becomes a fire menace when dry, and abates non-compliant lots at the owner's expense, with unpaid costs becoming a special assessment on the property tax bill.

Key details: Code chapter: Ontario MC Ch. 6-9 (Weeds and Refuse Abatement), Sec. 6-9.01 to 6-9.15. Nuisance declaration: Sec. 6-9.02(a). Notice of Violation fee: $172 (Aug. 2025). Civil penalty: $500. Abatement cost: Actual contractor cost + $57 admin fee.

After a Notice of Violation, an owner who fails to abate is subject to City abatement of the nuisance, with the cost (including administrative and investigative costs) assessed against the property and constituting a personal obligation of the recipient (Sec. 6-9.02(b)). Program fees as of August 2025 include a $172 Notice of Violation, a $172 re-inspection fee, $500 civil penalties, and actual contractor abatement costs plus a $57 administration fee; unpaid amounts become a special assessment on the property tax bill, and a property may be sold by the tax collector after three or more years of delinquent assessments.

Compared to other cities, Ontario takes a harder line on weed ordinances. The enforcement and penalty structure reflects that.

Tree Removal & Heritage Trees

Private yard trees in Ontario can usually be removed without a city permit, but parkway street trees are city-owned and need a Public Works permit. Commercial landscape plan trees require plan revision.

Key details: Private yard trees: Generally no city permit. Street trees: City owned, permit required. Required landscape trees: Replace 1 for 1. HOA rules: May impose extra restrictions. Contractor license: California C-27 or C-61.

Illegal removal of a city street tree is cited by Public Works with mandatory replacement plus recovery costs. Removing required landscape plan trees at a commercial site triggers Planning enforcement and potentially a stop work order until replacement is approved.

Ontario is more permissive than most cities when it comes to tree removal & heritage trees. That said, there are still limits.

Tree Trimming

Ontario Municipal Code Sec. 7-3.13 makes the abutting property owner responsible for watering, trimming, and maintaining parkway vegetation, including trimming trees to a minimum clearance of eight (8) feet from grade. Planting or removing any parkway tree requires a City permit and must conform to the Master Plan of Parkway Trees; major pruning and tree surgery are handled by the City.

Key details: Code section: Ontario MC Sec. 7-3.13 (Landscaping parkways). Tree clearance: Minimum 8 feet from grade. Owner duty: Water, trim, and maintain abutting parkway vegetation. City duty: Median parkways, major pruning, tree surgery, high pruning. Tree planting/removal: City permit; conform to Master Plan of Parkway Trees.

Under Sec. 7-3.20, failure to comply with a notice of violation within forty-eight (48) hours is itself a violation, and each day of continued noncompliance is a separate offense. Where a violation is an immediate hazard, the City may eliminate it and recover the costs from the owner; the City may also correct the condition and levy the costs against the property when the owner fails to respond.

Water Restrictions

Ontario is in the Voluntary Conservation Stage of its Water Conservation Plan (Ontario Municipal Code Chapter 8A, sections 6-8.20 through 6-8.35). The City's WaterWise program asks residents to avoid watering lawns between 6:00 AM and 6:00 PM, prevent irrigation runoff, and stop hose-washing of paved surfaces; mandatory restrictions take effect only if the City Council declares a Stage 1 through Stage 6 shortage.

Key details: Code chapter: Ontario MC Ch. 8A (Water Conservation Plan), Sec. 6-8.20 to 6-8.35. Current stage: Voluntary Conservation Stage (no drought declared). Suggested no-water hours: 6:00 AM to 6:00 PM. Mandatory stages: Stage 1 (10%) through Stage 6 (50%+). Declaring authority: City Council (Sec. 6-8.22).

In the Voluntary Stage the WaterWise measures are requests, not enforceable mandates. If the City Council declares a Stage 1 through Stage 6 shortage, sections 6-8.33 and 6-8.34 authorize enforcement, including penalties and an appeal/hearing process; exceptions for recycled water and public-health uses are preserved under section 6-8.24.

Grass Height Limits

The City of Ontario's Weed & Refuse Abatement program requires that 'all brush must not exceed 6 inches in height' on vacant lots, enforced to prevent fire hazards. In parkways, Ontario Municipal Code Sec. 7-3.13 caps ground cover or shrubbery at eighteen (18) inches in height and bars dead, dying, or uncultivated vegetation under Sec. 7-3.12.

Key details: Vacant-lot brush limit: 6 inches maximum (Weed & Refuse Abatement). Parkway cover limit: 18 inches maximum (Ontario MC Sec. 7-3.13). Parkway condition: No dead, dying, or uncultivated vegetation (Sec. 7-3.12). Inspections: Twice yearly, spring and fall. Private lawns: No fixed lawn-height number; weed nuisance rules apply (Ch. 6-9).

Vacant-lot brush over 6 inches triggers the abatement process: a Notice of Violation and fee on the first inspection, then a civil penalty, re-inspection fee, and Notice of Intent to Abate on the second, after which a City contractor abates the lot at the owner's expense. Parkway violations follow Sec. 7-3.20, where noncompliance within 48 hours of notice is a separate daily offense and the City may correct the condition and levy costs against the property.

The Bottom Line

Compared to many U.S. cities, Ontario gives residents more room on landscaping rules. 3 of the 8 rules here are rated permissive. But permissive does not mean unregulated. There are still requirements, and the city does enforce them when violations are reported.

These rules come from Ontario's publicly available municipal code. For complete penalty schedules, exemption details, and answers to common questions, see the individual ordinance pages throughout this guide.