First you need to add some color and depth with a mix of evergreens and deciduous flowing plants will do that just fine. I don't have a clue what zone you are in but it looks like you have liriope or something similar along your sidewalk. I use a mower to cut mine down, did it last weekend, because the pips were pushing up through it and the previous year's growth looks ugly. Visit a garden center to get an idea of growth habit. Most of all you don't want plants that will grow higher then your windows. On the end of the house I'd plant a small flowering tree, so take your bed around to the side of the house. Look at rockspray cotoneaster, euonymous fortunei varities and some low growing deciduous flowering shrubs and perennials that are hardy for your zone.

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