The ability to grow any acid-loving plant depends greatly on the site selection and preparation.
Because of their shallow, fibrous root system, azaleas, rhododendrons and blue berries require a soil that is uniformly moist, but not saturated. Light, well drained soils should be AVOIDED. Maintaining a uniform moisture supply can be accomplished with irrigation and/or mulching. Heavy, poorly drained soils will result in loss of plants to root rot.
In addition to the physical soil requirements, azaleas, Rhododendrons and blueberries require and acid soil with the ph in the range of 4.5 to 5.5 for best results. Soils that are more alkaline than 5.5 will result in the plants not growing as well and becoming yellowish and more subject to winter injury. If your soil is too sulfate can lover the pH.
When planting it is important not to plant to deep. Roots of these acid-loving plants tent to be in the upper 4-6″ of soil and need to be near the surface for aeration. To plant, dig a shallow hole, deep enough to plant the top of the root gall at or slightly above the existing soil.
Mulching with wood chips, sawdust, pine needles or similar material to a depth of 3-5″ is beneficial for controlling weeds, retaining moisture and adding organic matter. In addition, mulching will eliminate the need for cultivation which can cause injury to the shallow root systems.
When using a sawdust mulch it is necessary to replace the nitrogen lost in the decomposition process by fertilizing with a high nitrogen fertilizer.
Once planted, azaleas, Rhododendrons and blueberries benefit from the application of acid forming fertilizer, such as ammonium sulfate, to maintain soil acidity and supply nutrients. Specially formulated fertilizers for acid-loving plants are also available and are of great benefit. Fertilizers are best applied in the spring or early summer.