Gravel, Decomposed Granite and Soil Delivery in Gilbert, AZ

Heat, sun and little rain

Rainfall numbers here come from the NOAA normals station at Tempe Asu, AZ, about 8 miles away, which averages 8.8 inches of precipitation in a year. With so little rain, stone surfaces rarely wash out from steady showers. The threat comes from the few big storms that drop a lot of water fast on ground that cannot take it in.^[1]

Snowfall at Tempe Asu averages 0.0 inches a year. Desert sun is the bigger force on a yard, baking dark surfaces and drying exposed soil until it cracks.^[1]

The station counts 10 days a year with a low at or below 32 F. A handful of frosty mornings will not lift a gravel drive, but frost-tender plants such as young citrus may need a cover on those nights.^[1]

At Tempe Asu, the median last spring freeze date is February 13. The median first fall freeze date is December 5. Most planting goes in during the cooler months near either end of the warm season, when new roots face less heat stress.^[1]

Many desert yards include a retention basin, a shallow low area that holds storm water until it soaks in. Line its floor with River Rock or Riprap so the water does not scour the clay loam, and keep Decomposed Granite and loose mulch out of the inflow path, where a heavy flow would carry them off.^[1],[2]

Clay loam over old desert deposits

The USDA soil survey maps the ZIP's center point as Contine clay loam, and Contine accounts for 100 percent of that map unit. Clay loam has enough clay to feel sticky when wet and to set hard as brick when dry.^[2]

Shrink-swell in the top 100 cm is rated high, at 7.5 percent. A wet spell swells this soil, and the long dry months shrink it again, opening cracks at the surface. Pavers, slabs and stone edging laid straight on it can lift and drop with those changes unless a firm base sits between them and the clay.^[2]

The survey rates Contine as well drained but places it in hydrologic soil group C, where water soaks in slowly. Desert storm water runs across clay loam rather than into it. Grade every surface so runoff heads to a planted basin or a rock-lined swale and stays away from the house.^[2]

Dry clay loam is hard to dig, and wet clay loam smears and clogs tools. Many crews soak an area lightly the day before they dig, so the soil is damp but not muddy.^[2]

Beneath the clay loam, the USGS geologic map shows Late and middle Pleistocene surficial deposits at the center point. The unit is a mix of gravel, sand, silt and clay laid down in the Middle Pleistocene. Deposits like this can hold hard, cemented layers and buried cobbles, so a deep post hole may need a digging bar.^[3]

The ground at the center point stands 1,220 feet above sea level. On flat desert ground, even a small rise or dip shapes where storm water pools, so check the yard after a storm before you set a final grade.^[4]

Rounded cobbles turned up in a dig make handy edging for a dry creek bed, and any surplus can be mixed into a bed of River Rock for a natural look.^[3]

Decomposed Granite or crushed stone for a backyard

Two materials cover most open ground in a desert backyard. Decomposed Granite has fine particles that bind when wetted and rolled, so it forms a firm, smooth surface for paths, seating areas and play space. It blends with the desert palette and stays cooler underfoot than many dark stones.^[1],[2]

3/4" Crushed Stone or 3/8" Crushed Stone gives a looser, more textured cover that drains instantly and stays put on a slope. Crushed stone handles rain splash from a roof edge better than Decomposed Granite, which can wash where water hits it hard.^[2]

Many yards use both: Decomposed Granite for walking areas, crushed stone or River Rock in the low spots and along roof lines where water falls. Landscape fabric under either one slows weeds, and steel edging keeps the boundary clean.^[2]

The walk from the driveway to the front door takes the most foot traffic in a front yard. On clay loam, set pavers or flagstones on a compacted bed of Road Base and Concrete Sand, or build a path of Stone Dust Screenings compacted in thin layers. Edge either one firmly so the swelling soil does not push the borders out of line.^[2]

An RV or trailer pad on clay loam

Side-yard parking for an RV or a trailer is a frequent job on single-family lots. On high swell clay loam, the pad needs a thick compacted base to spread the weight and buffer the soil movement. Strip the top few inches, wet the clay lightly, and compact it before anything goes on top.^[2]

Lay a woven geotextile fabric, then build up Road Base or 1-1/2" Crushed Gravel in compacted lifts. Crushed Concrete is another strong base that packs tight. Finish with Driveway Gravel or 3/4" Crushed Stone, and slope the pad slightly toward the street so storm water leaves it.^[2]

Asphalt Millings make a firm, dark surface for a pad that sees heavy use, and they bind further in summer heat. Whatever the surface, edge it with concrete curbing or steel so the stone stays inside the lines.^[2]

Desert beds and trees on clay loam

Clay loam holds nutrients well but drains slowly, so a new bed benefits from Compost worked into the top layer to loosen it. For vegetables and flowers, raised beds filled with Garden Soil give roots a better start than native clay.^[2]

Mulch saves water in the desert. Wood Chips or Brown Shredded Mulch under trees and shrubs shade the root zone and slow evaporation. Black Shredded Mulch absorbs more heat, so use it in shaded spots rather than full sun.^[1]

When planting a tree in clay loam, dig wide rather than deep and backfill with the native soil mixed with a little Compost. A basin of River Rock around the tree, set a little away from the trunk, directs irrigation water to the roots.^[2]

Frost cloth over young citrus and other tender plants on the few cold nights near the median last freeze date in February saves a lot of replanting.^[1]

Houses in 85233 and across Gilbert

By the Census count, ZIP 85233 holds 15,711 housing units. Detached single-family houses make up 80 percent of that total.^[5]

The median home in ZIP 85233 dates to 1994. Owners occupy 73 percent of the occupied homes in the ZIP.^[5]

Gilbert as a whole counts 100,336 housing units, and 82 percent of them are detached houses.^[5]

The citywide median build year is 2003.^[5]