Answer: With the exception of boxwood, there are very few tall, narrow-growing evergreens that thrive in full shade. So, instead of trying to coax a shrub to grow in the area, why not consider placing a trellis on top of the wall and planting an evergreen vine? You can train a vine such as Trachelospermum (star jasmine) or Parthenocissus (Virginia Creeper) onto a trellis to fill in the void without having to worry about it outgrowing the small planting space. Good luck with your landscape!
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