Answer: It is a bit difficult to make specific suggestions without knowing which time of day the area is shaded, and when it is sunny. If it is sunny in the afternoon or for more than a few hours, you may need to use plants that prefer sun rather than shade. The type of soil there, as well as if it tends to be extra wet or dry will also make a difference in your plant selection, as will the width and height of the area you want to fill. Most perennials bloom for only a short time, so you may want to select a specific season when the planting would look good, or try for a continues series of blooms.
There are so many different perennials available, I would suggest you work with your local county extension and/or professionally trained nursery staff to analyze the growing conditions where you want to plant, and identify some that will thrive in that location, then select the ones you like best from among those.
Good luck with your planting!
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