Answer: In your area the soil is usually naturally on the acid side unless you have been adding lime to make it more neutral. But as a starting point you would need to test the soil pH and see where it is now. Based on the test results, you might need to acidify it for the azalea and probably would need to for the azalea.
Both plants like soil that is high in organic matter, evenly moist yet well drained, and it must be an acid soil. The blueberries need it extremely acidic while the azaleas are a bit more adaptable. This can be done by adding elemental sulfur or iron sulfate. (Some people will recommend aluminum sulfate but this can cause aluminum toxicity.) It usually takes a while for the pH to change, it is a gradual process and you will need to retest and follow up with it periodically.
These plants like similar soil but in my experience most azaleas do better in morning only sun or very bright dappled light all day while blueberries need more sun -- a minimum of six hours including the hour of noon, and longer is fine. Here is some information on growing blueberries and preparing soil for them that might be helpful. The points on soil preparation would apply equally well to azaleas.
Good luck with your new plants!
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