Soil pH in Okanogan, WA: Lime or Sulfur?

Typical topsoil pH in Okanogan, WA

Typical topsoil in Okanogan, WA is pH 6.45, already right for vegetable garden (6-7). Test before adding anything.

What Okanogan needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, tomatoes, strawberries, roses, pink hydrangeas.
• Sulfur: potatoes 1.2 lb/100 sq ft; blueberries 1.8 lb/100 sq ft; azaleas and rhododendrons 1.4 lb/100 sq ft; blue hydrangeas 1.4 lb/100 sq ft.

What to do next

If your test lands near 6.45, 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 1,669,827 surveyed acres in Okanogan, WA, 62% are near neutral (6.5-7.3), 32% are moderately acidic (5.5-6.5), 6% are strongly acidic (below 5.5), 1% are alkaline (above 7.3). Mapped soils run from pH 4.4 to 10.1, a spread of 5.7 units across 1,139 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 7.2% clay and 2.65% organic matter, which this site treats as sandy. Moving it one pH unit takes about 3 lb of lime or 1.2 lb of sulfur per 100 sq ft. 1% of mapped components carry free carbonate (lime already in the ground).

Okanogan against the rest of Washington

pH 6.45 is right at the Washington median of 6.41. 20 of 39 Washington counties have more acidic topsoil. Nationally it is more alkaline than the US county median of 6.05.

Closest in pH within the state: Cowlitz (5.74), Thurston (5.76), Skamania (5.86), Spokane (6.41), Kittitas (6.47), Pend Oreille (6.49), Chelan (6.5), Klickitat (6.53).

The range in Washington runs from Grays Harbor at 4.93 to Adams at 7.45; Okanogan sits 60% of the way up.