Soil pH in Santa Clara, CA: Lime or Sulfur?

Typical topsoil pH in Santa Clara, CA

Typical topsoil in Santa Clara, CA is pH 6.44, already right for vegetable garden (6-7). Test before adding anything.

What Santa Clara needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, tomatoes, strawberries, roses, pink hydrangeas.
• Sulfur: potatoes 2.1 lb/100 sq ft over 2 applications; blueberries 3.2 lb/100 sq ft over 2 applications; azaleas and rhododendrons 2.8 lb/100 sq ft over 2 applications; blue hydrangeas 2.8 lb/100 sq ft over 2 applications.

What to do next

If your test lands near 6.44, you can skip lime and sulfur for lawn (cool-season grass), vegetable garden, tomatoes, strawberries, roses, pink hydrangeas.

How mixed the soil is

Of the 472,727 surveyed acres in Santa Clara, CA, 62% are near neutral (6.5-7.3), 34% are moderately acidic (5.5-6.5), 4% are alkaline (above 7.3). Mapped soils run from pH 5.6 to 8.2, a spread of 2.6 units across 238 soil components. 62% of the land falls in one class, so the county figure is a fair first guess for most yards here.

Clay, organic matter and rates

Topsoil here averages 20.9% clay and 1.62% organic matter, which this site treats as loam. Moving it one pH unit takes about 7 lb of lime or 2.3 lb of sulfur per 100 sq ft. 1% of mapped components carry free carbonate (lime already in the ground).

Santa Clara against the rest of California

pH 6.44 is 0.1 below the California median of 6.54. 26 of 58 California counties have more acidic topsoil. Nationally it is more alkaline than the US county median of 6.05.

Closest in pH within the state: Glenn (6.34), Napa (6.37), Plumas (6.4), Santa Cruz (6.42), San Diego (6.46), San Francisco (6.5), Madera (6.58), Solano (6.63).

The range in California runs from Del Norte at 5.43 to Imperial at 8.16; Santa Clara sits 37% of the way up.