Soil pH in Houston, TX: Lime or Sulfur?

Typical topsoil pH in Houston, TX

Typical topsoil in Houston, TX is pH 5.63, too acidic for vegetable garden. Expect roughly 6.3 lb of lime per 100 sq ft, but only after a soil test confirms it.

What Houston needs, by plant

• Already in range: potatoes, strawberries, azaleas and rhododendrons.
• Just outside, test first: blueberries (off by 0.1), blue hydrangeas (off by 0.1).
• Lime: lawn (cool-season grass) 6.3 lb/100 sq ft over 2 applications; vegetable garden 6.3 lb/100 sq ft over 2 applications; tomatoes 6.3 lb/100 sq ft over 2 applications; roses 6.3 lb/100 sq ft over 2 applications; pink hydrangeas 4.2 lb/100 sq ft.

What to do next

If your test confirms pH near 5.63, spread about 63 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 687,827 surveyed acres in Houston, TX, 50% are moderately acidic (5.5-6.5), 40% are strongly acidic (below 5.5), 10% are near neutral (6.5-7.3). Mapped soils run from pH 4.3 to 7.9, a spread of 3.6 units across 90 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 13.5% clay and 1.4% 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. 1% of mapped components carry free carbonate (lime already in the ground).

Houston against the rest of Texas

pH 5.63 is 1.8 below the Texas median of 7.43. 24 of 254 Texas counties have more acidic topsoil. Nationally it is more acidic than the US county median of 6.05.

Closest in pH within the state: Wood (5.58), Cherokee (5.6), Rusk (5.6), Camp (5.63), Nacogdoches (5.68), Smith (5.7), Jefferson (5.71), Titus (5.74).

The range in Texas runs from Hardin at 4.64 to Upton at 8.19; Houston sits 28% of the way up.