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 is the best time to plant hydrangeas in North Jersey? I can never seem to get the plant to flower. I have 2 rose bushes that I need to plant. I live in Colorado and have a north facing front and south facing back. Where is the best place to plant them and how? Do hydrangeas grow in Florida? Can raspberry endless summer grow in full afternoon sun?