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 What shade loving plants besides hostas will tolerate dry, heavy clay soil? I just purchased Endless Summer® hydrangeas. Can I leave them potted until next spring to plant without injury? HOW DEEP DO I PLANT CORAL MAGIC CRAPE MYRTLES? What type of fertilizer is the best or is blueberry fertilizer just as good?