Different types of plants each require varying degrees of soil acidity. Some plants are even very sensitive to soil pH.  Generally, soils in moist climates tend to be acid and those in dry climates are alkaline. A soil with a pH lower than 7.0 is an acid soil and one with a pH higher than 7.0 is alkaline.  The soil must be adjusted to suit the plant that will occupy that area if it is not already within that plants requirement range.  pH” is a measure of your soil’s acidity or alkalinity. Each plant in your garden or yard has an ideal pH range that it will thrive in. This ideal range varies from plant to plant. If your garden soil is outside of this ideal range, the vital nutrients and minerals your plants need may become “locked up” in the soil, and the roots are unable to absorb them.

Sweet, sour, or bitter are common terms to describe soil ph. Sweet soil is the mid range, or ideal pH levels for most plants. Sour soils are acidic soil, with a low pH level. Some plants prefer a slightly acidic soil. Bitter is used to describe alkaline soils or high pH soil. Nutrients can get “locked up” in the soil? The mid range of the pH scale is the optimal range for bacterial growth to promote decomposition, a process that releases nutrients and minerals, making them available to your plants. Mid range pH is also the ideal range for growth of soil microorganisms that convert nitrogen in the air into a form that your plants can use. Outside of the ideal range, both processes are increasingly inhibited.

Many good garden centers will even gladly pH test a soil sample for you, or you can buy an inexpensive pH test kit at most nurseries, or hardware stores.  These test kits generally consist of a test tube, some testing solution and a color chart. You put a sample of your soil in the tube, add a few drops of test solution, shake it up and leave it for an hour or so to settle.  The solution in the tube changes color according to the pH of your soil. Compare the color of the sample with the color chart that came with the kit. Matching colors will tell you the pH of your sample. The better kits will also advisory booklets about how to interpret your result.  You should test your soil pH once every three years.

Once you have determined the pH you can amend the soil, if needed to accommodate the plants in your garden using materials commonly available at your local garden center. You can also find out information on the Internet and gardening sites.

It is generally easier to make soils more alkaline than it is to make them more acid. Because different soil types react in different ways to the application of lime you will have to add more lime to clay soils and peaty soils than you will in sandy soils to achieve the same result.

To increase your pH by 1.0 point and make your soil more alkaline.  Add 4 ounces of hydrated lime per square yard in sandy soils.  Add 8 ounces of hydrated lime per square yard in loamy soils.  Add 12 ounces of hydrated lime per square yard in clay soils.  Add 25 ounces of hydrated lime per square yard in peaty soils.  Correction of an overly acid soil should be considered a long-term project, rather than trying to accomplish it in one year. It is better to test your soil each year and make your adjustments gradually. The addition of hardwood ash, bone meal, crushed marble, or crushed oyster shells will also help to raise the soil pH.

If your soil needs to be more acidic, sulfur may be used to lower the pH if it is available. To reduce the soil pH by 1.0 point, mix in 1.2 oz of ground rock sulfur per square yard if the soil is sandy, or 3.6 oz per square yard for all other soils. The sulfur should be thoroughly mixed into the soil before planting. Sawdust, composted leaves, wood chips, cottonseed meal, leaf mold and especially peat moss, will lower the soil pH.

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