Soil pH in Flathead, MT: Lime or Sulfur?

Typical topsoil pH in Flathead, MT

Typical topsoil in Flathead, MT is pH 6.02, already right for vegetable garden (6-7). Test before adding anything.

What Flathead needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, strawberries, roses, pink hydrangeas.
• Just outside, test first: tomatoes (off by 0.2), potatoes (off by 0), azaleas and rhododendrons (off by 0).
• Sulfur: blueberries 2.3 lb/100 sq ft over 2 applications; blue hydrangeas 1.8 lb/100 sq ft.

What to do next

If your test lands near 6.02, 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 2,535,502 surveyed acres in Flathead, MT, 40% are moderately acidic (5.5-6.5), 29% are near neutral (6.5-7.3), 29% are strongly acidic (below 5.5), 2% are alkaline (above 7.3). Mapped soils run from pH 5 to 9.1, a spread of 4.1 units across 1,282 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 12.7% clay and 2.6% 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. 2% of mapped components carry free carbonate (lime already in the ground).

Flathead against the rest of Montana

pH 6.02 is 1.28 below the Montana median of 7.3. 0 of 56 Montana counties have more acidic topsoil. Nationally it is more acidic than the US county median of 6.05.

Closest in pH within the state: Ravalli (6.02), Lincoln (6.09), Mineral (6.1), Missoula (6.29).