Sometimes called moss phlox because its tiny, prickly green foliage persists year round, creeping phlox (Phlox subulata) is admired in late spring to early summer when it is clothed in a carpet of flowers. Many varieties exist today, providing choices in blossom color ranging from white to pink and lilac-lavender, and some with bi-colored blossoms. Grow this perennial in moist, well-draining soil in a sunny location in the garden, but if irrigation is lacking or natural rainfall is low, plant it in a partially shaded spot to increase vigor. Creeping phlox is best in U.S. Department of Agriculture hardiness zones 3 through 8.
Wait until after the creeping phlox plant has finished its annual flowering. Depending on climate, flowering may begin as early in mid-spring but will certainly end no later than early summer.
Trim back the tips of all stems on the plant with a heavy-duty scissors or hand-held pruning shears. Reduce the overall length of the stems no more than 20 to 30 percent their original length. For example, if your plant was originally 6 inches tall, it should be no shorter than 4 inches tall when you're done.
Whisk away cuttings from the plant occasionally as you prune to help you better visualize your progress. Use your open hand and fingers to flick or rake away the cuttings to also allow more light and air to reach the plant to encourage regrowth.
Touch-up pruning cuts if the plant overall looks tattered with uneven stems. The pruning doesn't need to be perfectly even since the plant will soon rejuvenate, but you want a somewhat attractive plant after the task, too.
Prune back errant or intruding stems that are growing into nearby plants or covering rocks or the sidewalk. Cut these stems back to 1 to 2 inches from the ground, as the other stems will soon rejuvenate to hide these stem stumps. Consider making irregular-length pruning cuts if you are trimming stems in a straight-line along a sidewalk--you don't want an unnatural straight edge on a creeping phlox plant.