The words on a landscape quote, translated

Base rock

Crushed aggregate laid and compacted under paving to spread load and stop the surface moving. Depth is specified to the soil and to what the surface will carry, and it is compacted in lifts rather than dumped in one layer. The single most common place a cheaper patio quote is cheaper.

Compaction in lifts

Placing fill or base rock in shallow layers, compacting each one before the next goes on. Material dumped in a single deep layer cannot be compacted through its full depth, so it settles later and takes whatever was built on it down too.

Decompaction

Mechanically breaking up a compacted soil layer so roots and water can move through it. Standard first step on new-build lots, where the pad was compacted to engineering specification for structural reasons. Usually followed by incorporation of organic amendment.

Hydrozone

A group of plants with similar water needs, irrigated together on one valve. Hydrozoning is the reason a controller can water a thirsty entry bed and a dry back slope correctly at the same time. Mixing water needs on a single valve guarantees one group is always wrong.

Cycle and soak

Splitting an irrigation station run into two or three shorter cycles with a gap between them, so each pass stays under the rate the soil can absorb. On the tighter soils around Folsom this is the difference between watering the root zone and watering the gutter.

Precipitation rate

How fast an irrigation zone applies water, usually expressed in inches per hour. Compared against infiltration rate to work out how long a station can run before producing runoff. Different head types have very different rates, which is why mixing them on one zone waters unevenly.

Infiltration rate

How fast soil accepts water, in inches per hour. Falls as the soil wets up. When the precipitation rate exceeds it, the surplus becomes runoff regardless of how much the plants need.

Emitter

The fitting on a drip system that releases water at a rated flow, commonly 0.5, 1, or 2 gallons per hour. Pressure-compensating emitters deliver their rated flow across a range of pressures, which matters on long runs and on slopes.

Inline emitter tubing

Drip tubing with emitters manufactured into it at fixed spacing. Faster to install across a planted area than individual emitters on stakes, and less prone to being knocked out of position during maintenance.

Pressure regulator

A device that reduces incoming pressure to what drip components are rated for, commonly around 25 to 30 psi. Without one, emitters over-deliver, fittings blow off under summer load, and the zone waters unevenly. Belongs on every drip valve, alongside a filter.

Backflow preventer

A device stopping irrigation water from being drawn back into the potable supply. Residential systems commonly use anti-siphon valves or a pressure vacuum breaker. Where a testable assembly is installed, water agencies in this region typically require periodic testing by a certified tester.

Valve manifold

A group of irrigation control valves assembled together, usually in a box, fed from a common mainline. Grouping valves makes them findable years later, which matters more than it sounds: locating buried valve boxes is often the first day of any irrigation repair on an older system.

MWELO

California's Model Water Efficient Landscape Ordinance. Applies to new landscapes of 500 square feet or more and rehabilitated landscapes over 2,500 square feet, where the project requires a permit, plan check, or design review. Requires a water budget calculation, hydrozone plan, and irrigation schedule in the drawing set.

Water budget

The maximum applied water allowance for a landscape under MWELO, calculated from landscape area and local reference evapotranspiration. The planting and irrigation design has to come in under it.

Evapotranspiration (ET)

The combined water lost from soil by evaporation and from plants by transpiration, the figure that describes how much water a landscape demands. Varies by month and by region, and smart controllers use local ET data to adjust run times automatically.

Seasonal adjust

A controller setting that scales every station run time by a percentage, so one change adapts the whole programme to the season. Four adjustments a year cut annual landscape water use more than most equipment upgrades.

Retaining wall

A structure holding back soil at a change of level. Generally exempt from building permit up to four feet measured from the bottom of the footing, unless it supports a surcharge. Above that, it needs engineering and a permit.

Surcharge

Load above a retaining wall beyond the soil itself: a driveway, a structure, a pool, or a slope climbing away behind it. Where a surcharge exists, the standard permit exemption does not apply at any wall height.

Face foot

Height times length of the exposed face of a wall, the unit segmental wall work is normally priced in. A wall 3 feet high and 30 feet long is 90 face feet. Courses buried below grade add cost without adding face area.

Geogrid

A stiff synthetic mesh laid in horizontal layers extending back into the retained soil behind a segmental wall. It ties the soil mass into the structure, which is what allows taller walls to be built in block rather than poured concrete.

Drain rock

Clean, washed, angular rock placed behind a retaining wall to let groundwater move down to a perforated pipe rather than loading the wall. Separated from the retained soil by filter fabric so fines do not migrate in and clog it.

Levelling pad

The compacted crushed-rock base under the first course of a segmental wall, cut level and buried below finished grade. Everything above it inherits whatever accuracy it was built to.

French drain

A gravel-filled trench with a perforated pipe at the bottom, wrapped in filter fabric, that collects subsurface water and carries it to an outlet. Distinct from an area drain, which collects surface water at a low point.

Daylight

Where a drainage pipe discharges to open air at a lower elevation. A drain pipe that does not reach daylight or an approved outlet is a pipe that fills up and stops working, which is a surprisingly common finding on older systems.

Swale

A shallow, gently sloped depression that moves surface water across a site without a pipe. Often the cheapest drainage solution on a lot with usable fall, and it can be planted so it reads as part of the garden rather than as infrastructure.

Positive drainage

Grade that falls away from a structure so water leaves rather than pools. On patios the normal figure is about a quarter inch of fall per foot, enough to shed water and not enough to feel like a slope underfoot.

Sheet mulching

Killing a lawn in place by covering it with overlapping cardboard and several inches of mulch, then planting once it has broken down. Cheaper than excavation, keeps organic matter in the soil, and needs two to four months. Not reliable against bermudagrass.

Establishment period

The first two to three years after planting, during which a drought tolerant plant still needs regular irrigation while it develops the root system that makes it drought tolerant. The stage most low-water planting failures happen in.

Defensible space

The managed area around a structure in a designated fire hazard severity zone, organised in bands with progressively lower fuel volume moving outward. About spacing, fuel continuity, and maintenance rather than clearing to bare ground.

Ember zone

The immediate few feet around a structure, where wind-blown embers are most likely to find something to ignite. Detailed with non-combustible surfacing rather than bark mulch, and kept clear of stored timber and accumulated litter.

Dredger tailings

Ridges of washed cobble and gravel left by gold dredging, which worked the American River floodplain around Folsom until the Natomas No. 6 shut down in February 1962. Ground carrying them drains sharply, holds little water, and has to be dug rather than augered.

C-27 licence

The Landscaping Contractor classification issued by the California Contractors State License Board. The minor-work exemption allowing unlicensed jobs rose from $500 to $1,000 on January 1, 2025 under AB 2622, and does not apply where the work needs a permit or the person employs anyone on it.

Most of these come up in the cost guide and the retaining wall guide, where they appear in context rather than alphabetically.