Soil pH is a measure of how acidic or alkaline your soil is. For the cool-season grasses that grow across Suffolk County — tall fescue, Kentucky bluegrass, perennial ryegrass — the ideal range is 6.0 to 7.0, with 6.5 being the sweet spot. When pH drifts outside that range, nutrients get chemically locked in the soil. Your grass can’t access them, no matter how much fertilizer you apply.
What makes this especially relevant in Suffolk County is that our soils are naturally prone to acidity. The sandy glacial outwash deposits that make up most of the county’s ground drain quickly, leach calcium and magnesium faster than denser soils, and drift acidic over time. Add in the decomposing oak and pine leaves common in neighborhoods like Smithtown, Setauket, and Port Jefferson, and many lawns are fighting a pH problem that never gets addressed — just covered up with more product.