Moss Phlox, or Creeping Phlox, likes a soil that is rich in humus. The soil must drain well so that the plant is not bothered by wet feet. It is fine to mulch up to the perimeter of the plant. Wait until bloom time has passed, and then shear your plant quite harshly. This shearing may help to produce a second round of blooms, less impressive than the first. If no new blooms appear, the shearing will ensure good, fresh growth of foliage. Remember, this plant loves full sun.