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 type of fertilizer should I use on my hydrangea? I have a couple endless summer hydrangeas and they never bloom until end of Sept. early October. What do I need to do to get them to bloom earlier in the summer to be able to enjoy the blooms more than a month before a frost. I gave acidic fertilizer but maybe not doing it correctly or enough. I just received 4 plants. Should I wait until the fall to plant them in the ground and just keep them in their pots for now? What shade loving plants besides hostas will tolerate dry, heavy clay soil?