Why are my phlox different colors and heights this year?

There are several reasons this may be happening. University of Memphis Director of Landscape Joellen Dimond says new seeds may be growing that are crosses of last year’s plants. Retired UT Extension Agent Mike Dennison says most plants do not change their physical characteristics from year to year, but phlox can change flower color through the year to attract different kinds of pollinators.
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Related Resources:
Phlox
Handling and Caring for Garden Phlox