I am trying to determine which plants like an acid soil and which prefer an alkaline site. Are there guides to the proper acidity for plants?
Let’s start by saying most plants prefer a slightly acid soil. If ever in doubt, you can usually be successful growing the common landscape plants in a soil with a pH between 5.5 and 6.5. A few that grow best in a more acid soil below pH 5.5 include azaleas and blueberries. Some that like the pH 7, a neutral soil, or slightly above include the herbs of borage, sage, tarragon and thyme. Usually references do give a general guide to the soil acidity desired. They often mention a plant needs an acid or slightly acid soil, and you can assume this is in the 5.5 to 6.5 range. Only in a few instances is a more detailed discussion of a plant’s acidity requirement needed. Having the soil acidity at an exact pH is not that important for most plants.
