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 Should I cut the almost dead flowers off? How do I dead head your roses? We just planted 3 of them. Thank you. My hydrangeas are looking droopy are they supposed to look like that? I received hydrangea this past spring for my birthday in May. Do I need to cover it for the winter?