Getting shrubs to grow into a dense screen in the shade is difficult. They need light to support dense leaf growth. If you could brighten the shade or plant them on the edge where light is brighter, that would probably work much better. Some shrubs to consider are Southern Wax Myrtle (probably the best), Carolina Cherry Laurel, and Camelia (if your soil pH is not too high). Japanese Aucuba (Aucuba japonica) is the densest in shade but only get to about 5-6 feet tall, although this may well be large enough for a screen.
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