pH runs from 0 to 14, with 7 neutral. Each whole number is a tenfold change, so a soil at 8.0 is ten times more alkaline than one at 7.0. Grass does not care about the number directly; it cares about what the number does to the nutrients. Iron, manganese, and phosphorus, in particular, lock up as soil turns alkaline, which is why a yellowing St. Augustine lawn on Gulf Coast sand so often turns out to be an iron problem caused by a pH problem.
Why Florida Soil Is Different
Florida does not have one soil. Much of the interior is acidic sand. Along the Gulf Coast, where Bayside Sod’s customers are, soils built on shell and limestone, and yards filled with shell rock or concrete rubble during construction, run alkaline, often above 7.5. Irrigation water from wells drilled into limestone adds more alkalinity every time the sprinklers run, and reclaimed water can too. The result is a lawn that gets plenty of fertilizer and cannot use it.
The sandy texture matters as well. Sand holds little organic matter and few nutrients, and it drains fast, so whatever you apply moves through quickly. Corrections to pH do not last as long as they would in a heavier soil, which is why testing has to be a habit, not a one-time step.
How to Test Soil pH
Testing is inexpensive and does not need a professional. A garden-center pH probe or test strip kit gives a rough number. For a result you can act on, send a sample to your county Extension office; the University of Florida IFAS soil testing lab reports pH plus the nutrients that matter for turf, and the county office will tell you how to collect and where to drop it.
Collect the sample from 3 to 4 inches below the surface, from several spots across the lawn, and mix them together. Take a separate sample from any area that looks different from the rest. Test at least once a year, and always before a new sod installation, because it is far easier to amend bare soil than an established lawn. Bayside Sod’s Turf Care plans include soil testing for that reason: the fertilizer program is built from the result, not guessed.
Adjusting Soil pH
If the soil is too alkaline (the common Gulf Coast case), elemental sulfur lowers pH as soil bacteria convert it to sulfuric acid. The rate depends on the test result and the lawn’s square footage, and it works over months, not days; expect one to two seasons for a full point of change, and retest before applying more. Where the alkalinity comes from shell or limestone in the ground, sulfur is a maintenance treatment rather than a cure, because the shell keeps dissolving.
If the soil is too acidic, lime raises pH. Dolomitic lime also adds magnesium. Follow the rate on the soil test, not the bag, and give it three to six months before retesting.
In the meantime, a lawn that is yellow on alkaline soil usually responds within days to a foliar iron application (chelated iron, sprayed on the leaves), because it bypasses the soil. That is a symptom fix, not a pH fix, but it keeps the lawn green while the sulfur works.
Keeping It in Range
Natural processes and your own irrigation water shift pH gradually, so retest every year and adjust the fertilizer and amendment plan to the result rather than repeating last year’s schedule. Watch for the signs of drift between tests: yellowing that fertilizer does not fix, thinning in the same spots each spring, or a lawn that greens up after rain but not after irrigation, which points at the irrigation water.
A healthy lawn starts below the grass. Test the soil, correct the pH, and the sod you lay on it can use what you give it. For a soil test with a fertilizer program built from it, see Turf Care; for a sod quote, request one here or call (941) 702-1746.