Soil pH in Gilpin, CO: Lime or Sulfur?

Typical topsoil pH in Gilpin, CO

Typical topsoil in Gilpin, CO is pH 6.24, already right for vegetable garden (6-7). Test before adding anything.

What Gilpin needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, tomatoes, strawberries, roses, pink hydrangeas.
• Just outside, test first: potatoes (off by 0.2), azaleas and rhododendrons (off by 0.2).
• Sulfur: blueberries 2.8 lb/100 sq ft over 2 applications; blue hydrangeas 2.3 lb/100 sq ft over 2 applications.

What to do next

If your test lands near 6.24, you can skip lime and sulfur for lawn (cool-season grass), vegetable garden, tomatoes, potatoes, strawberries, roses, azaleas and rhododendrons, pink hydrangeas.

How mixed the soil is

Of the 77,098 surveyed acres in Gilpin, CO, 60% are moderately acidic (5.5-6.5), 38% are near neutral (6.5-7.3), 3% are strongly acidic (below 5.5). Mapped soils run from pH 5 to 7.2, a spread of 2.2 units across 252 soil components. No single class covers 60% of the county, so two gardens a few miles apart here can need opposite treatments. Test your own bed.

Clay, organic matter and rates

Topsoil here averages 11.8% clay and 1.56% 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.

Gilpin against the rest of Colorado

pH 6.24 is 0.93 below the Colorado median of 7.17. 3 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: San Juan (5.53), Hinsdale (5.93), Clear Creek (6), Lake (6.37), Teller (6.41), Grand (6.42), Summit (6.42).

The range in Colorado runs from San Juan at 5.53 to Alamosa at 8.28; Gilpin sits 26% of the way up.