Soil pH for the Red Plum Tree

Why pH is Important

• Soil pH measures the acidity of the soil. Plants need different levels of acidity for their systems to function at full capacity. The pH level affects which nutrients roots can absorb, type and amount of soil bacteria, the structure of the soil and whether toxic elements, such as aluminum, hang around near your plants. Low numbers signify acidic soil, a pH of 7.0 is neutral and higher numbers indicate alkaline soil. Without the proper soil pH, red plum trees won't thrive and might not produce the fruit you're hoping for.

Soil pH for Red Plums

• Red plums survive in a rather wide selection of pH levels, but they do best in soils with a pH of 5.5 to 6.5. This means the soil is slightly acidic, which helps the roots absorb minerals and nutrients. This pH level is ideal for all soil types, especially clay -- clay tends to become more granulated in this pH range, making it easier to work with and better able to drain while holding nutrients.

pH Variations

• Red plum trees can grow in soil with levels up to 8.0, according to the Old Farmer's Almanac. Higher soil pH might make it more difficult for the tree to absorb nutrients such as phosphorous and iron, so when the pH levels top the neutral mark, modify the soil pH to one more suitable for maximum plum production.

Testing and Soil Amendments

• Many garden supply stores sell home soil pH test kits, which typically involve you spooning a small amount of soil into an included solution and matching the solution's color to a pH chart. These easy-to-use test kits help you determine whether you should amend the soil to bring it to a pH your red plum tree will thrive in. If the number is below 5.5, it's too acidic; adding substances such as lime or gypsum can help raise the pH. If the pH level is higher than 6.5, it's too alkaline; mixing products such as ammonium sulfate or sulfur into the soil can help lower the pH.