Soil pH in San Francisco, CA: Lime or Sulfur?

Typical topsoil pH in San Francisco, CA

Typical topsoil in San Francisco, CA is pH 6.5, already right for vegetable garden (6-7). Test before adding anything.

What San Francisco needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, tomatoes, strawberries, roses, pink hydrangeas.
• Sulfur: potatoes 2.3 lb/100 sq ft over 2 applications; blueberries 3.5 lb/100 sq ft over 2 applications; azaleas and rhododendrons 3 lb/100 sq ft over 2 applications; blue hydrangeas 3 lb/100 sq ft over 2 applications.

What to do next

If your test lands near 6.5, 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 6,394 surveyed acres in San Francisco, CA, 74% are moderately acidic (5.5-6.5), 24% are alkaline (above 7.3), 3% are near neutral (6.5-7.3). Mapped soils run from pH 5.8 to 8.5, a spread of 2.7 units across 9 soil components. 74% 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 16.1% clay and 2.16% 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. None of the mapped components carry free carbonate.

San Francisco against the rest of California

pH 6.5 is right at the California median of 6.54. 28 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: Plumas (6.4), Santa Cruz (6.42), Santa Clara (6.44), San Diego (6.46), Madera (6.58), Solano (6.63), Contra Costa (6.69), Santa Barbara (6.69).

The range in California runs from Del Norte at 5.43 to Imperial at 8.16; San Francisco sits 39% of the way up.