Soil pH in Washington, PA: Lime or Sulfur?

Typical topsoil pH in Washington, PA

Typical topsoil in Washington, PA is pH 6.04, already right for vegetable garden (6-7). Test before adding anything.

What Washington 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 6.04, 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 536,780 surveyed acres in Washington, PA, 67% are moderately acidic (5.5-6.5), 21% are strongly acidic (below 5.5), 12% are near neutral (6.5-7.3). Mapped soils run from pH 5 to 7.1, a spread of 2.1 units across 133 soil components. 67% 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 22.7% clay and 2.42% 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.

Washington against the rest of Pennsylvania

pH 6.04 is 0.73 above the Pennsylvania median of 5.31. 65 of 67 Pennsylvania counties have more acidic topsoil. Nationally it is more acidic than the US county median of 6.05.

Closest in pH within the state: Lawrence (5.84), Delaware (5.86), Montgomery (5.91), Bucks (5.92), Greene (6.07).

The range in Pennsylvania runs from Forest at 4.57 to Greene at 6.07; Washington sits 98% of the way up.