Looking for a Border plant for a cottage gardening look??

ok...i have a cottage garden look flower bed; the back drop is a scalloped white picket fence; in the bed which is 25 feet long/3 feet wide are abelia shrubs (only 2 feet high so far)....they are spaced evenly across the bed; also evenly spaced are autum rose sage plants...about 2 feet high; also spaced evenly across the bed are pink begonias; on one end of the bed is a huge climbing pink rose bush; i had my heart set on varigated lariope to edge the bed, but it is looking too 'harsh' compared to the soft english garden look of the bed; any suggestions?? what is a border that will stay year after year that goes with the cottage garden theme??