Range

• Gardenias prefer soil with a pH of 5 to 6, according to the National Gardening Association. Permanently changing naturally soils with a naturally high pH proves difficult. Consider growing other plants in such areas or saving gardenias to use as container plants, suggests University of Florida Extension.
  
  

Importance

• Lower soil pH increases mineral availability for gardenias. Soils with a pH above 7.0 results in mineral deficiencies in gardenias, especially iron.
  
  

Tip

• Have a soil sample analyzed at your local county extension office before planting gardenias. This provides detailed information on the soil pH level, in addition to information on the nutrient and mineral content of the soil.