Answer: Pieris is hardy into zone 5 if there is protection from the wind. Morning sun should be fine for it as well as for smaller varieties of azalea and rhododendron. You might look into some of the hardier varieties of these to go along with the pieris. They all need an acid soil that is humusy, evenly moist and yet very well drained. You mgiht want to run some basic soil tests to make sure your soil would suit these plants. Alternatively, you might be able to trim back the yews very hard (in early spring) and renew them rather than replace them. Your county extension should be able to help you with the soil tests and interpreting the results as well as make suggestions for foundation shrubs that would do well there.
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