Do Azaleas & Blueberries Mix Well?

Acid Soil pH

• The pH rating scale measures soil acid or alkaline content and has a point-range from 0 to 14, with 7.0 indicating neutral. Soils testing below 7.0 are classified as acid or sour; those above 7.0 are alkaline, basic or sweet. Scores are logarithmic; an acid soil with a score of 5.5 is 10 times more acidic than a soil scoring 6.5. A pH score indicates a soil's potential hydrogen-ion content; the quantity of hydrogen ions determines what nutrients the plant will be able to process from soil.

Required Soil Acidity Levels

• Azaleas, both deciduous and evergreen, are sub-genera of the genus Rhododendron. Originating as woodland plants, azaleas require a soil acidity of between 4.5 and 6.0 to grow. Blueberries, whether low-bush, high-bush or rabbit-eye, are also native to woodland areas. They require even more acid soil content, between 4.09 and 5.0, for healthy growth and fruit production. Testing soil before planting is essential for successful growing of these acid-lovers. Adding elemental sulfur, rotted leaf compost and other acidic organic amendments can make soil more acid, although you will need to make considerable efforts to modify soil with a pH of 6.0 or above.

Plant Hardiness

• While specific varieties of azaleas and blueberries have specific needs, there is a wide choice of climate-compatible plants. Depending on the variety, azaleas are hardy in U. S. Department of Agriculture plant hardiness zones 4 through 9, making them suitable landscape plants for all but the most extreme climates in the U.S. Lowbush (Vaccinium angustifolium) and highbush (Vaccinium corymbosum) blueberries are generally hardy in USDA zones 3 through 7, while rabbiteye (Vaccinium ashei) blueberries extend the growing range to USDA zones 7 through 9.

Soil Requirements

• Because both azaleas and blueberries have shallow root systems, they share needs for soil with a high component of organic matter, 3 percent or above, and excellent drainage. Growers warn against planting either in heavy clay soil and comment that neither tolerates having wet feet. Ideal soils for blueberries or azaleas are loamy, rich in humus and consistently moist but not soaking wet. Mulching with pine needles, hardwood sawdust or other organic materials can keep roots cool and retain surface moisture while supporting soil acidity.

Light

• Where azaleas and blueberries part company is in their needs for sunlight. Commonly forest understory plants, azaleas do best in dappled sunlight. Shallow roots and leaves are susceptible to scorching during prolonged periods of hot direct sun. Like most fruiting plants, although they can grow as ornamental shrubs in partial sun, blueberries require full sun to produce berries. One way to use both plant varieties in the same yard is to plant azaleas where they receive tree-canopy filtered light or a combination of morning sun and afternoon shade, while locating blueberries nearby in a sunnier part of the yard.