Soil pH in Jefferson, CO: Lime or Sulfur?

Typical topsoil pH in Jefferson, CO

Typical topsoil in Jefferson, CO is pH 6.72, already right for vegetable garden (6-7). Test before adding anything.

What Jefferson needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, tomatoes, roses.
• Just outside, test first: strawberries (off by 0.2), pink hydrangeas (off by 0.2).
• Sulfur: potatoes 2.8 lb/100 sq ft over 2 applications; blueberries 3.9 lb/100 sq ft over 2 applications; azaleas and rhododendrons 3.5 lb/100 sq ft over 2 applications; blue hydrangeas 3.5 lb/100 sq ft over 2 applications.

What to do next

If your test lands near 6.72, 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 313,055 surveyed acres in Jefferson, CO, 74% are near neutral (6.5-7.3), 22% are moderately acidic (5.5-6.5), 4% are alkaline (above 7.3). Mapped soils run from pH 5 to 8.2, a spread of 3.2 units across 394 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 16.9% clay and 2.53% 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. 7% of mapped components carry free carbonate (lime already in the ground).

Jefferson against the rest of Colorado

pH 6.72 is 0.45 below the Colorado median of 7.17. 11 of 63 Colorado counties have more acidic topsoil. Nationally it is more alkaline than the US county median of 6.05.

Closest in pH within the state: Summit (6.42), San Miguel (6.54), Gunnison (6.6), Larimer (6.6), Boulder (6.75), Custer (6.75), Douglas (6.81), El Paso (6.81).

The range in Colorado runs from San Juan at 5.53 to Alamosa at 8.28; Jefferson sits 43% of the way up.