The Prescriptive Path for Small California Landscapes

Who can use the checklist

The ordinance applies in the first place to new construction with a landscape area of 500 square feet or more that needs a building or landscape permit, plan check or design review, and to rehabilitated landscapes of 2,500 square feet or more with the same triggers (section 491(a)(1) and (a)(2); landscape area is defined in section 490.2(a)(41)).

Within that, the prescriptive option is written for new construction projects with a landscape area between 500 and 2,500 square feet (section 492(a), section 491.2(b)). Section 491(b) also states that a project of 2,500 square feet or less may take either route. Read together with section 491.2(c), which sends any landscape project of 2,500 square feet or greater to the performance option, the safe reading is that the checklist belongs to new construction under 2,500 square feet, and that a project sitting exactly on the line should ask its local agency which route it wants.

Using the checklist is all or nothing: compliance with the requirements of section 492 is mandatory and must be documented in the Landscape Documentation Package (section 492(b)). If one item does not fit your design, the performance path with its worksheet is always available instead.

The paperwork

The prescriptive package is short (section 491.4(a)). A project information sheet: date, applicant name and contact information for applicant and owner, project address, total landscape area in square feet, project type, water supply type and the retail water purveyor if you are not on a private well, and the applicant's signed statement agreeing to comply with the prescriptive option.

Plus a landscape design plan with the total landscape area and a breakdown of turfgrass and plant material, such as a plant legend. Compare that with the performance package, which needs six elements including a soil management report, grading and irrigation design plans and the full water worksheet (section 491.4(b)).

Soil first: the compost rule

Incorporate compost at a rate of at least four cubic yards per 1,000 square feet, worked six inches deep into the landscape area, unless a soil test says otherwise (section 492(c)(1)).

There is an exemption written into the same item: soils that already hold more than 6 percent organic matter in the top six inches are exempt from adding compost and tilling.

Irrigation requirements

The controller must be automatic and run on weather data or soil moisture data, with a rain sensor, and it must keep its settings in non-volatile memory (section 492(c)(2)(B) and (C)).

The system needs pressure regulation so it runs inside the manufacturer's recommended range, and a manual shut-off valve as close as possible to the point of connection (section 492(c)(2)(D) and (E)).

Emission devices must meet the 2020 ASABE/ICC 802 Landscape Irrigation Sprinkler and Emitter Standard, and installed sprinkler heads must document a low-quarter distribution uniformity of 0.65 or higher under that standard's protocol (section 492(c)(2)(F)). Non-rotating spray sprinkler bodies must meet the standard in Title 20, section 1605.3(x) of the California Code of Regulations (section 492(c)(2)(G)).

Two placement rules: strips of landscape less than 10 feet wide in any direction must use subsurface irrigation or another method with no waste, runoff or overspray (section 492(c)(2)(H)), and non-residential projects with 1,000 square feet or more of landscape must install a dedicated irrigation meter or private submeters (section 492(c)(2)(A)).

Plants, turf and mulch

For homes, climate adapted plants that need occasional, little or no summer water (an average WUCOLS rating of 0.3) must cover 75 percent of the landscape area, not counting areas permanently and solely dedicated to edible plants and areas using recycled water. Non-residential projects must hit 100 percent (section 492(c)(3)(A) and (B)).

Turfgrass is capped at 25 percent of the landscape area for homes and banned entirely on non-residential projects. It cannot go on slopes steeper than one foot of rise per four feet of run, and it is prohibited in parkways under 10 feet wide unless the parkway sits next to a parking strip used to enter and exit vehicles; any parkway turf must use subsurface irrigation or another no-overspray method (section 492(c)(3)(C)).

Finish with mulch: a minimum three-inch layer on all exposed soil in planting areas, except turf areas, creeping or rooting groundcovers, or direct-seeded areas where mulch gets in the way (section 492(c)(4)).

Finishing the project

The designer of record must make the plants identifiable to the inspector at final inspection, by botanical name, common name or cultivar as specified in section 53481 of the Food and Agricultural Code (section 492(d)).

The permit applicant then hands a certificate of completion package, per section 494(a), to both the property owner and the local agency (section 492(e)). That closes the prescriptive route: checklist built, documented, inspected, certified.