Orange County, CA Invasive Plant Rules: Prohibited Species (2026)
Key Facts
- Authority
- OC Ag Commissioner
- State Law
- CA Food & Ag Code §5004
- Quarantines
- Asian citrus psyllid
- MWELO
- 500+ sq ft compliance
Summary
California's noxious weed list applies in Orange County. The OC Agricultural Commissioner enforces plant quarantines and pest regulations. The county's Water Efficient Landscape Ordinance requires new landscaping to use drought-tolerant species.
5004. “Noxious weed” means any species of plant that is, or is liable to be, troublesome, aggressive, intrusive, detrimental, or destructive to agriculture, silviculture, or important native species, and difficult to control or eradicate, which the director, by regulation, designates to be a noxious weed. In determining whether or not a species shall be designated a noxious weed for the purposes of protecting silviculture or important native plant species, the director shall not make that designation if the designation will be detrimental to agriculture.
(Amended by Stats. 1992, Ch. 556, Sec. 1. Effective January 1, 1993.)
Full Breakdown
The Orange County Agricultural Commissioner enforces California Food and Agriculture Code provisions regarding noxious weeds and plant quarantines. State-listed noxious weeds (giant reed, pampas grass, yellow starthistle) are subject to eradication orders. The OC Agricultural Commissioner also enforces quarantines against specific pests and plant diseases, including the Asian citrus psyllid quarantine that restricts movement of citrus plants. Under Orange County's compliance with the state Model Water Efficient Landscape Ordinance (MWELO), new landscaping projects over 500 square feet must meet water efficiency standards, limiting high-water-use turf and encouraging native and drought-tolerant plants. Orange County faces invasive species challenges including: Arundo donax in waterways, ice plant along coastal bluffs, and non-native grasses in wildland areas. The county's open space management programs include invasive species removal.
Violations & Fines
Violating plant quarantines can result in fines under the Food and Agriculture Code. MWELO non-compliance can delay project approvals and landscaping permits.
Frequently Asked Questions
What plants are prohibited in Orange County?
Does Orange County require drought-tolerant landscaping?
Sources & Official References
Other rules in Orange County
California rules heatmap·Compare Orange County to another location·View the California invasive plant rules overview
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