Soil pH

• Soil with a pH of 6.6 to 7.3 is considered neutral. Anything lower is acidic and anything higher is alkaline. Grapefruit trees are adaptable, but generally grow best in soil that is neutral to moderately alkaline, with an ideal range between 6.0 and 8.0.
  
  

Problems

• If the pH is too low for grapefruit trees -- as it frequently is in Florida and other citrus growing regions -- the most common problem is magnesium deficiency. This can cause leaves to turn yellow and fall off and twigs to become weak and die.
  
  

Solutions

• You can take a number of measures to raise soil pH. Using dolomite will raise the pH to between 6.0 and 6.5, and replenish magnesium at the same time. Liming, the process of adding crushed limestone to the soil, can also raise pH, and should ideally be done before grapefruit trees are ever planted.