pH is a measure of acidity and alkalinity, on a scale from 0 to 14. The lower the number, the more acid the soil. A pH of 7.0 is neutral, neither acid nor alkaline. (For a list of common substances and their pH, see the chart pH Scale.) Many of the chemical reactions that occur in all soils depend on the pH. The soil pH often determines what nutrients are available for plant use. Soils are rarely more acidic than 4.0 or more alkaline than 9.0. Most plants will grow in soils with a pH of 5.5 to 7.5. Some plants need acid soil (4.0 to 5.5). Others will tolerate alkaline conditions (7.5 to 9.0). (For a list, see Plants That Will Grow in Alkaline Soil (pH 7.5 to 8.4).) To determine your soil pH, have your soil tested (see Soil Testing).
Related Links
Acid Soil
Alkaline Soils
Salty Soil
Soil Testing
