Soil pH in Montgomery, MD: Lime or Sulfur?

Typical topsoil pH in Montgomery, MD

Typical topsoil in Montgomery, MD is pH 5.47, too acidic for vegetable garden. Expect roughly 7 lb of lime per 100 sq ft, but only after a soil test confirms it.

What Montgomery needs, by plant

• Already in range: potatoes, blueberries, azaleas and rhododendrons, blue hydrangeas.
• Just outside, test first: strawberries (off by 0).
• Lime: lawn (cool-season grass) 7 lb/100 sq ft over 2 applications; vegetable garden 7 lb/100 sq ft over 2 applications; tomatoes 7 lb/100 sq ft over 2 applications; roses 7 lb/100 sq ft over 2 applications; pink hydrangeas 5.6 lb/100 sq ft over 2 applications.

What to do next

If your test confirms pH near 5.47, spread about 70 lb of ground limestone per 1,000 sq ft of vegetable bed in 2 doses, ideally in fall.

How mixed the soil is

Of the 298,629 surveyed acres in Montgomery, MD, 66% are strongly acidic (below 5.5), 25% are moderately acidic (5.5-6.5), 9% are near neutral (6.5-7.3). Mapped soils run from pH 4 to 7, a spread of 3 units across 221 soil components. 66% 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 18.6% clay and 2.18% 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.

Montgomery against the rest of Maryland

pH 5.47 is right at the Maryland median of 5.49. 10 of 24 Maryland counties have more acidic topsoil. Nationally it is more acidic than the US county median of 6.05.

Closest in pH within the state: St. Mary's (5.2), Calvert (5.31), Harford (5.33), Somerset (5.35), Cecil (5.48), Wicomico (5.5), Kent (5.53), Dorchester (5.6).

The range in Maryland runs from Charles at 4.47 to Washington at 6.01; Montgomery sits 65% of the way up.