Soil pH in Miami-Dade, FL: Lime or Sulfur?

Typical topsoil pH in Miami-Dade, FL

Typical topsoil in Miami-Dade, FL is pH 6.91, already right for vegetable garden (6-7). Test before adding anything.

What Miami-Dade needs, by plant

• Already in range: lawn (cool-season grass), vegetable garden, roses.
• Just outside, test first: tomatoes (off by 0.1).
• Beds or pots instead: potatoes, strawberries, blueberries, azaleas and rhododendrons, blue hydrangeas, pink hydrangeas.

What to do next

If your test lands near 6.91, you can skip lime and sulfur for lawn (cool-season grass), vegetable garden, tomatoes, roses.

How mixed the soil is

Of the 85,599 surveyed acres in Miami-Dade, FL, 43% are alkaline (above 7.3), 28% are near neutral (6.5-7.3), 16% are moderately acidic (5.5-6.5), 14% are strongly acidic (below 5.5). Mapped soils run from pH 4.8 to 8.2, a spread of 3.4 units across 111 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 9.5% clay and 2.39% 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. 38% of mapped components carry free carbonate (lime already in the ground), enough that sulfur gets neutralised before it does much.

Miami-Dade against the rest of Florida

pH 6.91 is 1.66 above the Florida median of 5.25. 65 of 67 Florida counties have more acidic topsoil. Nationally it is more alkaline than the US county median of 6.05.

Closest in pH within the state: Pinellas (5.82), Sarasota (5.82), Brevard (6.04), Broward (6.25), Monroe (7.81).

The range in Florida runs from Franklin at 4.5 to Monroe at 7.81; Miami-Dade sits 73% of the way up.