"Creeping phlox" is sometimes a confusing appellation because it is applied to more than one species of phlox. The real creeping phlox is phlox stolonifera, hardy in U.S. Department of Agriculture plant hardiness zones 5 through 9. However, moss phlox (Phlox subulata), which is hardy in USDA zones 3 through 9, is often referred to as creeping phlox as well. Both have a low growth habit -- creeping phlox sometimes reaches 12 inches tall while moss phlox actually has a lower growth height, at 6 inches. Both spread along the ground via stolons, hence the name “creeping.”
Phlox is an excellent addition to containers. It not only provides the “ground cover” effect for a container planting, its foliage and flowers cascade down the sides, providing an additional layer of visual interest. Because of its trailing, mat-forming habit, creeping phlox makes a nice accent to taller, more erect container plants. Consider planting it with tall, graceful plants such as smooth hydrangea (Hydrangea arborescens), native to the eastern United States and hardy in USDA zones 3 through 9.
Containers allow you to create gardens in places where your natural allotment of soil is poor. When building a container garden, or even when planting phlox in a container on its own, provide for drainage by using containers with holes in the bottom. Also keep in mind that creeping phlox is a perennial. If you grow it as an accent to annuals, you’ll need to plant something in the place of the annuals when they die. Otherwise, you can mix it with other perennials for a longer-lasting effect.
Creeping phlox prefers a location in full sun or partial shade, with a medium amount of moisture. When growing in containers, plants lose water much more quickly than plants growing in the ground, so you have to keep a close eye on them. Enlist the kids in checking soil moisture; teach them to stick their fingers into the soil and, when it has dried out, to add more watering with a watering can.