In the picture above there is columbine, golden ragwort, and heucheras. A crape myrtle (on the right) gives us some summer color when in bloom on the corner of our front porch. The boxwood to the left is one of two that flank the pathway that goes underneath our side garden arbor. When you turn to the right you will see the front garden with its rock border. This garden is in transition at the moment. The daffodils are done blooming and the foliage is replenishing the energy the bulbs need to grow next year. Irises will take the stage next in this bed, many of which will be flowering within the next week.
To soften the borders I like to plant plants like phlox that crawl over the border. Phlox is not overly aggressive and is easily controlled by trimming after bloom. I have one plant that is sprawling on our sidewalk which has generated all kinds of roots underneath. After they finish blooming I'll take my clippings and plant them in other locations for spring color next year since the clippings are already rooted.
Our whole front garden area is bordered with rocks from the driveway to around the side of the house. It's fun to mix the natural roughly hewn stone with manufactured paver and patio blocks like around our front entry spot and our sitting wall border. Mixing the two types of stone makes the garden blend well with other natural elements.
Do you use rock and stone in your garden for borders?