Soil pH in Polk, FL: Lime or Sulfur?

Typical topsoil pH in Polk, FL

Typical topsoil in Polk, FL is pH 5.41, too acidic for vegetable garden. Expect roughly 3.3 lb of lime per 100 sq ft, but only after a soil test confirms it.

What Polk needs, by plant

• Already in range: potatoes, blueberries, azaleas and rhododendrons, blue hydrangeas.
• Just outside, test first: strawberries (off by 0.1).
• Lime: lawn (cool-season grass) 3.3 lb/100 sq ft; vegetable garden 3.3 lb/100 sq ft; tomatoes 3.3 lb/100 sq ft; roses 3.3 lb/100 sq ft; pink hydrangeas 2.4 lb/100 sq ft.

What to do next

If your test confirms pH near 5.41, spread about 33 lb of ground limestone per 1,000 sq ft of vegetable bed, ideally in fall.

How mixed the soil is

Of the 1,093,152 surveyed acres in Polk, FL, 60% are strongly acidic (below 5.5), 32% are moderately acidic (5.5-6.5), 5% are alkaline (above 7.3), 3% are near neutral (6.5-7.3). Mapped soils run from pH 3.6 to 8.2, a spread of 4.6 units across 331 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 7.3% clay and 2.28% 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. 4% of mapped components carry free carbonate (lime already in the ground).

Polk against the rest of Florida

pH 5.41 is 0.16 above the Florida median of 5.25. 42 of 67 Florida counties have more acidic topsoil. Nationally it is more acidic than the US county median of 6.05.

Closest in pH within the state: Volusia (5.31), Nassau (5.32), Okeechobee (5.33), Jackson (5.34), Glades (5.43), Lake (5.43), Flagler (5.46), Hillsborough (5.47).

The range in Florida runs from Franklin at 4.5 to Monroe at 7.81; Polk sits 27% of the way up.