Frequently Asked Questions

Permit Process

Is a permit required to build a greenhouse?

Yes. Before nursery owners construct greenhouses, they must obtain a land use building permit from the County. The level of the permit is dictated by the existing zoning of the parcel, the condition of the access road, and the size of the greenhouse.

There are four main levels of permitting for greenhouses: Plot Plan, Site Plan, Minor Use Permit, and Development Plan. The level of possible restrictions associated with the permit increase with the classification of permit. A Plot Plan permit is the least restrictive and a Development Plan is the most restrictive.

For example, more requirements could be placed on a smaller sized greenhouse located on an un-paved road than on a larger greenhouse located on a paved road. The smaller greenhouse could be required to have a mitigation plan to control dust or it might be required to pave part or all of its access road as part of obtaining the permit.

Why should greenhouses be allowed within the Rural Residential land use category?

This land use category is designed to be a blend of residences and various types of agriculture in an effort to maintain the rural character of land so designated. When the San Luis Obispo County Land Use Ordinance (LUO) was revised in January 1996, details about greenhouse permits were incorporated into section 22.08.054 – Nursery Specialties. This section of the Land Use Ordinance contains a chart showing the level of permit required which depends on the road condition and the size of the proposed greenhouse. Details about requirements and restrictions placed on greenhouses during the permit process are also outlined in this section of the LUO.

Are any permit requirements placed on greenhouses?

Yes, especially in the Residential Rural land use category. In 1996, members of the CCGGA worked closely with the SLO Planning Department during the revision of the SLO Land Use Ordinance (LUO). Various requirements and standards on greenhouses were placed in the LUO in an effort to minimize or eliminate potential problems that may arise at the agriculture/residential interface. Since it is the priority of CCGGA and its members to be good neighbors within our community, the Association worked to ensure that residential concerns were thoroughly addressed within the Land Use Ordinance.

What are some of these requirements?

In the Residential Rural land use category, the level of permitting is determined by greenhouse size and the existing road improvement level. Permit requirements may include: mitigation measures for controlling dust, possible road improvements, minimum site size, setbacks, screening and other construction design standards.


Are pesticides used in growing greenhouse plants as well as field plants?

Yes. To grow any plant successfully, controlling the pests that can damage or kill those plants is critical. Over the past few years, the trend has been to use safer pesticides or adopt an “Integrated Pest Management” (IPM) program that reduces pesticide use. IPM programs often incorporate the use of “beneficial or predatory insects” that may eat or disable harmful insects.

Very strict application rates, techniques, and record keeping are required by state and federal law. Nurseries are inspected at a minimum of once yearly and 100% of pesticides used must be reported to the County Agricultural Commissioner via detailed monthly reports.

These strict controls and comprehensive regulations on the use of pesticides by nurseries are in direct contrast to the home and lawn garden whose use of pesticides is unregulated and unmonitored.

Does anyone regulate the use of pesticides in greenhouses?

Yes. The SLO County Agricultural Commissioner’s Office is responsible for regulating the use of pesticides to protect the safety of workers, the general public, and the environment. Through its pesticide regulatory program, the County monitors pesticide use, audits pesticide records, enforces laws and regulations, provides user education, and responds to public complaints and questions about the legal use of pesticides. For more detailed information, the SLO Department of Agriculture publication titled “Is This a Legal Use of Pesticides?” is available by mail. Call (805) 781-5910 or (805) 473-7090 to request a free copy.

How do I know which pesticides my greenhouse neighbor is using?

Under California law, 100% of all pesticides used at nurseries must be reported monthly to the County Agriculture Department. The California Public Records Act mandates the Agricultural Commissioner to release documents related to pesticide applications to the public upon request. These may include: Restricted Materials Permits, pending Notices of Intent, Use Reports, and records of enforcement actions and investigations. These documents are considered public records. Call the SLO County Agricultural Commissioner’s Office at (805) 781-5910 or (805) 473-7090 to request this information.

How do I know my greenhouse neighbor is using pesticides properly?

California has the strictest pesticide use regulations in the United States. Before growers can use a pesticide, they must obtain a permit from the County Agriculture Department; take an exam regarding safety, storage, and proper use of pesticides; and have adequate safe pesticide storage available. Growers must also report all quantities of pesticides used to the Agriculture Department on a monthly basis via a detailed report. The greenhouse sites, storage areas, and in-house records are also periodically checked by a County Department of Agriculture Inspector for compliance. Inspectors conduct regular surveillance oversight and perform unannounced inspections of pesticide applications. Growers may receive written warnings, fines, or suspension of their permit if they are not using pesticides in accordance with state and federal laws. The Agriculture Department checks every pesticide use reported on the monthly report for proper dilution rate, EPA registration number, and California registration. Call the SLO County Agriculture Department at (805) 781-5910 or (805) 473-7090 to request additional information.

Are the pesticides used in greenhouses contaminating my well water?

In the Nipomo Mesa area, pesticides have not been detected through official governmental testing in any well water.

Each year, pursuant to the Pesticide Contamination Prevention Act, the California Environmental Protection Agency (Cal EPA) Department of Pesticide Regulation sample California well water and test for pesticide residues. All 50 of the wells tested in San Luis Obispo County during the period of July 1998 through June 1999 were found to be free of pesticide residue. The results of the annual well water tests are contained in the Well Inventory Database maintained by the California Environmental Protection Agency. For additional information or details, contact the Cal EPA at: 830 K Street, Sacramento, CA 95814 or visit their web site at http://www.cdpr.ca.gov/

Who can I call if I think I’m being exposed to pesticides from an application taking place at a nursery?

The San Luis Obispo County Department of Agriculture will respond to complaints/concerns about pesticide applications. Call the Arroyo Grande Office at (805) 343-0645 or the Main Office at (805) 781-5910, or the Toll-Free Complaint Hot Line (toll free and confidential) at 1-800-528-9333.

Screening & Buffering

What is the CCGGA’s position on screening greenhouses from the view of neighbors or drive-by traffic?

As part of its Good Neighbor Policy, the association is committed to screening greenhouse facilities from public view and encourages effective landscape screening by its members.

Why are some nurseries screened and others not?

Some of the nurseries that have been long established may not have heavy plant screenings. In most cases, these nurseries were originally built when the surrounding area was more rural and there was no one from whom to screen the view of the facilities. In other cases, planting additional trees may block light that is essential for crop growth. However, CCGGA encourages all its members to screen their greenhouses.

Aren’t growers required by the County to establish such screening?

Only when applying for a new land use permit. For instance, if an applicant requests a reduction in the distance required for its property line setback, a comprehensive landscape (screening) plan will be required as part of the permit application made to the County Planning Department. In addition, the Environmental Coordinator will require that the facility be screened at least 50% from public roads.

Why haven’t some growers put in screening in the past?

Concerns over blocking out light to the greenhouses have been the primary reason for not establishing heavy screening. In addition, an abundance of trees and shrubs can create fire hazards. These plantings can also be hosts for pests and/or diseases that can destroy greenhouse crops. In the past, many growers planted Leyland cypress or Monterey pines, both of which have turned out to be poor choices as they are now dying due to diseases and pests.

How do growers go about selecting trees and shrubs for screening use?

The County Planning Department has a list of approved plants for landscaping. These plants are selected for their drought resistance. Other sources of information are local wholesale container nurseries, retail nurseries, landscape contractors, and the UC Cooperative Extension.

What are “Agricultural Buffers”?

One of the objectives of the SLO County Agricultural Commissioner’s Office is to protect the public’s health and safety while promoting and protecting agriculture. One way this is accomplished is by avoiding land use conflicts at the agriculture/residential interface. Potential conflicts could include pesticide use, noise, dust, vandalism, agricultural burning, and so on.

In order to avoid or minimize problems, the Agriculture Commissioner’s Office makes recommendations on building setbacks — i.e., buffers — and/or screening techniques (e.g., walls, landscaping) between development projects, such as homes or schools, and agricultural property. These buffers are the most effective mitigation measure. Buffer distance ranges vary according to the type of agricultural use that is adjacent to the proposed development.

These buffers are usually imposed on residential subdivisions or major development projects taking place adjacent to existing agricultural land use. They may be imposed on a greenhouse property if it were a new business enterprise on property next to existing residences.

For additional information, please contact the SLO Agriculture Commissioner’s Office at (805) 781-5910 or (805) 473-7090.


Most CCGGA businesses are located on land that was zoned Agriculture (A-1) when these greenhouses and nurseries were originally established. These businesses are all, by definition, part of the “Farm” classification and are therefore ruled and dictated by the same guidelines and limitations as farms. Although some of the land on which these greenhouses and nurseries exist has been re-zoned Residential-Rural by the County to allow residential construction, the “Rural” designation maintains the use of the land for agricultural purposes and is true to the intent of the original zoning