Apparently there are some pretty tall phlox varieties: Border phlox Phlox paniculata “David” is one; Mile High Pink Phlox is another; Caspian, Hesperis, Kirmeslandler, Old Cellarhole, Robert Poore, Russian Violet are others. Heights of these mention range from suggested 5 feet to about 6 feet. It may be that you have perfect conditions that inspire yours to reach even higher! As for how they got into your garden…an animal or bird may have transported the seed but it’s impossible to know for certain.
Apparently there are some pretty tall phlox varieties: Border phlox Phlox paniculata “David” is one; Mile High Pink Phlox is another; Caspian, Hesperis, Kirmeslandler, Old Cellarhole, Robert Poore, Russian Violet are others. Heights of these mention range from suggested 5 feet to about 6 feet. It may be that you have perfect conditions that inspire yours to reach even higher! As for how they got into your garden…an animal or bird may have transported the seed but it’s impossible to know for certain.