Question WHEN IS THE BEST TIME TO PLANT CREEPING PHLOX? Answer Creeping phlox is a tough plant! You can plant it either spring or fall. If you plant it now, you will be able to enjoy it early spring when it flowers. Tags: CareDesignFAQProjects Related Questions Why is the plant turning black? I would like to put the hydrangea I just bought in a large pot instead of in the ground, is that possible? How and when do you prune hydrangeas? DOES FIRST EDITIONS HAVE EVERGREEN CRAPE MYRTLES?