The best range is between 4.5 to 6.0. Azaleas and rhododendrons growing in a low pH of 3.5 to 4.5 will be healthy, but will often grow at a slower rate than normal. Foliage of these plants growing in a soil pH of 6.5 and above may appear yellow, an indication of chlorosis.Click to see full answer. In this way, how do I acidify my azalea soil?Look for fertilizer containing ammonium nitrate, ammonium sulfate, or sulfur-coated urea. Both ammonium sulfate and sulfur-coated urea are good choices for making soil acidic, especially with azaleas. However, ammonium sulfate is strong and can easily burn plants if not used carefully.Beside above, why do Azaleas need acidic soil? The plant could be growing where it is too wet or too dry or could need additional nutrients, such as nitrogen, sulfur or iron. However, rhododendrons, azaleas, blueberries, heathers and hydrangeas typically need a strong acidic environment, and if the soil has the wrong pH, are unable to absorb nutrients. Besides, how do you lower the pH of azaleas? Home gardeners can lower their soil pH by adding sphagnum peat moss to the soil. (The pH of sphagnum peat moss generally ranges from 3.0 to 4.5.) When planting azaleas and rhododendrons, dig a wide, shallow hole. Backfill with a mixture that is half soil and half moistened sphagnum peat moss.Are azaleas acid loving?Popular plants such as azaleas, rhododendrons, blueberries, strawberries and heathers, are all acid-loving, meaning they need a soil pH of about 5.5. Knowing whether your soil is acidic or not is the first step to healthier plants season after season.