These clump forming plants with small, heart-shaped leaves are the darlings of the edging world. All summer and into autumn, the plants produce huge numbers of slender stems, each carrying a single bell-shaped flower in a clear shade of blue and with a 2" upturned face. Run a line of these along the base of that sunny garage wall - you'll forget that it was ever weedy and ugly there.
For planting info see the "Campanula Planting Guide" link below.