Answer: There are many possible choices. Your plant selection will depend on which way it faces and if it is sunny or shady, whether or not it is windy there, and on the soil type as well as whether the soil is normal, extra wet or on the dry side in terms of moisture levels. You will also need to decide if you want annual and/or perennial flowers, deciduous or evergreen shrubs, andhow much maintenance you can provide for the planting. In addition to length you need to know the depth and also height of the space the plants can fill when they mature (eg will they block a window if they get tall?). Your local nursery staff should be able to help you with identifying plants that would do well there, then you can pick out the ones you like best from those.
Generally speaking you would need to prepare the soil by clearing it and loosening it down about ten inches, adding ample amounts of organic matter such as good quality compost, then level it. You would also want to use a layer of organic mulch several inches thick year round to help keep down weeds, retain soil moisture, and feed the soil as it rots down over time. You would also want to run some basic soil tests to check nutrient levels and pH, then add fertilizer or other amendments as indicated by the soil tests.
I hope this helps you start planning your project!
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