50 Fresh Seeds Phlox Annual Red Phlox, sometimes called ?garden phlox? or ?summer phlox,? is an easy, low-maintenance plant that can look great anywhere in your garden but which is particularly suited to borders.By the time you finish our in-depth growing guide, you are going to feel like a phlox expert. We are going to teach you the ideal conditions for growing phlox, how to plant and care for this perennial, what varieties to consider, and more. Type: Flower. Color: Red. Height: 8" to 20" Tall. Width: 8" to 12" Spread. Season: Annual. Zones: 3 to 10. Environment: Full Sun / Partial Shade.