pH Requirements for Geraniums

Soil pH

• pH is the measure of the acidity or alkalinity of soil, and most plants require a specific pH range. Low pH indicates acidity and high pH indicates alkalinity. Soil with a pH of 3.5 is considered extremely acidic, while soil with a pH of 9.0 is considered strongly alkaline. Neutral soil has a pH between 6.6 and 7.3.

Geranium Optimal Range

• Geraniums generally prefer soil that is slightly to moderately acidic. The specific pH depends on what variety of geranium you intend to plant. Ivy geranium and regal geranium require soil with a pH between 5.5 and 6.0, while zonal geranium needs a pH between 5.8 and 6.3.

Problems

• A number of problems can occur in geraniums if they are planted in soil with an incorrect pH. Geraniums are susceptible to iron and manganese toxicity at pH balances below 5.8, and hybrid varieties can develop brown spots or fail to bloom.