Azaleas prefer acidic soil with a pH of 5 to 6.5. Soil pH is a very important factor in plant health – if the soil is too acidic or too alkaline, plants will be unable to absorb nutrients properly, and your garden won’t grow. The degree of acidity and alkalinity is measured on a scale of 0-14, with a pH of 7 neutral, 0-7 acidic, and 7-14 alkaline. The ideal soil pH for vegetables and lawn grasses is 6.5, just a little on the acidic side. A soil test is needed to determine the pH of your soil.