En EspaŅol

Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

Help us grow by giving to the Plant Database Fund or by becoming a member

Did you know you can access the Native Plant Information Network with your web-enabled smartphone?


Ask Mr. Smarty Plants

Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

Search Smarty Plants
See a list of all Smarty Plants questions
Can't find the answer in our existing FAQs, submit a question to Mr. Smarty Plants.
Need help with plant identification, visit the plant identification page.
rate this answer
Not Yet Rated

Monday - October 13, 2008

From: Clarendon Hills, IL
Region: Midwest
Topic: Diseases and Disorders, Herbs/Forbs
Title: Mildew in Phlox paniculata
Answered by: Barbara Medford


I planted garden phlox (phlox paniculata) in my front landscaping and it is suffering from mildew. It is wet on that side due to a down spout and it may benefit from being split. Does anyone know of a treatment to eliminate the mold? They really do not flower well.


Your native Phlox paniculata (fall phlox) is probably not in any danger from the mildew, although it does make the plants somewhat unattractive. Mildew is common in the Fall, because of cool nights and still-warm days. Too much water in a flower bed, such as from a downspout, can cause other problems in plants, like root rot. You might want to consider finding a way to channel the outflow from your downspout away from the flower bed. Since your phlox is a perennial, you might also consider dividing it and moving it to another area. The best preventions of mildew are good air circulation and sunshine. Since it isn't always possible to provide those, read this article from About.com Organic Gardening on   Preventing and Controlling Powdery Mildew. One tip we picked up from this and other sources, which surprised us, is that one of the best treatments for powdery mildew is a good spray of water on the affected plants. It should be done early in the day, so that the water will have plenty of time to dry before sundown, but it does seem to work. You could go on to try the baking soda spray solution mentioned in the article, although we have heard mixed reports on the efficacy of that method. There are fungicides available, but that is likely overkill for this problem. Rake up the fallen leaves and blooms, and keep the area clean, so mildew can't winter over.

Phlox paniculata




More Diseases and Disorders Questions

White fuzz on pine tree bark in Dartmouth MA
July 13, 2010 - We have white fuzz on our pine tree bark?
view the full question and answer

Problems with sunflowers in Florida
November 03, 2006 - I planted sunflowers on the west side of my house where I have previously planted them and they grew wonderfully. These new ones, however, seem to be dying, (less than 2 weeks). I bought the plants at...
view the full question and answer

Freeze damage to non-native Philodendron selloeum in Deltona FL
June 22, 2010 - My philodendrons selloeum died this past winter in the freeze,came back slowly this spring and now are suffering with very small deformed leaves. Some do grow but are getting large brown dry areas on ...
view the full question and answer

Non-blooming Tecoma stans in Fredericksburg, TX
June 30, 2008 - We have an esperanza plant purchased last year from Walmart and planted outside before winter. It flowered excellently last year. Just before winter we cut it back to about a foot. So far this summer ...
view the full question and answer

Insect infestation of plants, dog and home
September 14, 2008 - I have plants that some kind of bug is killing them, my fan plam, ficus tree and other plants. The leaves are drying up and falling off. Apparently, they also are infestion my apartment. I feel them c...
view the full question and answer

Smarty Plants's Facebook profile Support the Wildflower Center by Donating Online or Becoming a Member today.

Mr. Smarty Plants wants you to be his Facebook friend. Click the Facebook icon to add yourself to Mr. Smarty Plants list of friends.
© 2015 Lady Bird Johnson Wildflower Center