Soil pH in Delaware, PA: Lime or Sulfur?

Typical topsoil pH in Delaware, PA

Typical topsoil in Delaware, PA is pH 5.86, just outside the 6-7 range for vegetable garden. Test first; it may need nothing.

What Delaware needs, by plant

• Already in range: potatoes, strawberries, azaleas and rhododendrons.
• Just outside, test first: lawn (cool-season grass) (off by 0.1), vegetable garden (off by 0.1), roses (off by 0.1), pink hydrangeas (off by 0.1).
• Lime: tomatoes 4.2 lb/100 sq ft.
• Sulfur: blueberries 2.1 lb/100 sq ft over 2 applications; blue hydrangeas 1.4 lb/100 sq ft.

What to do next

If your test lands near 5.86, you can skip lime and sulfur for lawn (cool-season grass), vegetable garden, potatoes, strawberries, roses, azaleas and rhododendrons, pink hydrangeas.

How mixed the soil is

Of the 96,525 surveyed acres in Delaware, PA, 49% are strongly acidic (below 5.5), 28% are near neutral (6.5-7.3), 24% are moderately acidic (5.5-6.5). Mapped soils run from pH 4 to 7.2, a spread of 3.2 units across 205 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 16.1% clay and 2.61% 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.

Delaware against the rest of Pennsylvania

pH 5.86 is 0.55 above the Pennsylvania median of 5.31. 62 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: Adams (5.78), Chester (5.79), Lancaster (5.81), Lawrence (5.84), Montgomery (5.91), Bucks (5.92), Washington (6.04), Greene (6.07).

The range in Pennsylvania runs from Forest at 4.57 to Greene at 6.07; Delaware sits 86% of the way up.