Troubleshooting
Garden Phlox 'David' problems — and how to fix them
Garden Phlox 'David' (Phlox paniculata) is generally forgiving once you match its basics, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Powdery mildew
'David' has good resistance, but crowded, poorly ventilated conditions still invite infection. Thin clumps every 2-3 years and water at soil level.
Spider mites
In hot, dry spells tiny mites cause a fine speckling on leaves. Increase humidity around plants and use a suitable miticide or insecticidal soap.
Crown rot
Wet winters can kill crowns in poorly draining soils. Improve drainage or grow on a slight mound.
Leaf spot (Septoria)
Brown spots with purple margins on lower leaves; remove affected foliage and avoid overhead watering.
Eelworm (stem nematode)
Stunted, distorted shoots in spring; no chemical cure — lift and destroy affected clumps and replant in a fresh site.
Prevent garden phlox 'david' problems before they start
Most garden phlox 'david' issues are care-mismatch, not bad luck. Dial in the basics:
Garden Phlox 'David' problems — FAQ
Why is my garden phlox 'david' powdery mildew?
'David' has good resistance, but crowded, poorly ventilated conditions still invite infection. Thin clumps every 2-3 years and water at soil level.
Why is my garden phlox 'david' spider mites?
In hot, dry spells tiny mites cause a fine speckling on leaves. Increase humidity around plants and use a suitable miticide or insecticidal soap.
Why is my garden phlox 'david' crown rot?
Wet winters can kill crowns in poorly draining soils. Improve drainage or grow on a slight mound.
Why is my garden phlox 'david' leaf spot (septoria)?
Brown spots with purple margins on lower leaves; remove affected foliage and avoid overhead watering.
Why is my garden phlox 'david' eelworm (stem nematode)?
Stunted, distorted shoots in spring; no chemical cure — lift and destroy affected clumps and replant in a fresh site.