The Q&A Archives: Powdery Mildew On Hardy Phlox

Question: For many years I have had great success with a white colored hardy phlox growing in a northeast section of one of my flowerbeds. Two years ago they developed mildew that was very resistent to treatment. My question; has the mildew developed permanently in this particular bed, and should I remove any or all of the affected phlox that return, since they all eventually develop the same mildew?

Answer: Mildew is a fungus, so it can be carried over from year to year on old plant debris. A good fall clean up is very important for this reason. I would also suspect that, over the years, all of your plants have grown larger and as a result the air flow is not as open as it once was. You might try thinning the phlox by removing some of the stems in the spring and make sure the plants are divided frequently so they are not crowded. You might also try a different type of phlox; "David" is reliably mildew free in my garden.

« Click to go to the homepage

» Ask a question of your own

Q&A Library Searching Tips

  • When singular and plural spellings differ, as in peony and peonies, try both.
  • Search terms are not case sensitive.

Today's site banner is by Char and is called "'Diamond Head' Sunrise"