Native Plants
![](../_images/smarty_plants.gif)
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.
Did you know you can access the Native Plant Information Network with your web-enabled smartphone?
Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.
![](../_images/mr_smarty_plants_logo_web_200w.jpg)
rate this answer
![](../_images/star_00.gif)
Sunday - June 20, 2010
From: Philadelphia, PA
Region: Mid-Atlantic
Topic: Non-Natives, Diseases and Disorders
Title: Powdery growth in hydrangea in Philadelphia
Answered by: Barbara Medford
QUESTION:
My hydrangea plants have a weird growth on their leaves that looks like white rice. It looks like it would be powdery if brushed, but I don't want to touch it for fear that it some type of mold. Any idea what it could be?ANSWER:
There is one hydrangea native to Pennsylvania, Hydrangea arborescens (wild hydrangea), but we're betting you have a hybrid in your garden. Philadelphia, in the southeast corner of Pennsylvania, is in USDA Hardiness Zone 6b to 7. We think you probably have a form of Hydrangea macrophylla, also known as bigleaf, French, garden or florist's hydrangea. It is hardy to Zone 6, which means it can do well in your area. However, it is a native of Japan, and therefore out of our range of expertise. At the Lady Bird Johnson Wildflower Center we are committed to the growth, protection and propagation of plants native not only to North America but to the area in which that plant is being grown.
The best source we found for information on hydrangeas was The United States National Arboretum Hydrangea Questions and Answer. From that same site, you should read the part on Are hydrangeas bothered by diseases or insects?. Here is an excerpt from that portion that probably applies to your situation:
"For the bigleaf hydrangea, the major disease problem is powdery mildew (see image at right). It is most common on plants growing in shade and under high humidity conditions. Powdery mildew infested leaves are covered with a light gray powdery-looking substance. Purple splotches may also appear. Powdery mildew rarely kills plants, but is unattractive. Powdery mildew may occur on other hydrangea species, but is most severe on bigleaf hydrangea."
To us, mildew doesn't look like rice on a leaf, but it certainly isn't attractive. Another source for information on disease of hydrangeas is this one from the University of Florida Extension Service, Hydrangea macrophylla.
Native Hydrangeas from our Native Plant Image Gallery:
More Non-Natives Questions
Drooping leaves on iris in Phenix City, AL
May 02, 2009 - I had a bed FULL of iris rhizomes so I thinned them out and made two beds. They flowered perfectly but some of the flower stalks and some of the leaves began drooping over. The flowering is over. The ...
view the full question and answer
Pruning non-native oleanders
September 28, 2011 - I have an oleander that has become to "leggy". I read the pruning instructions, but where I want to prune, there are not any leaf nodes. Can I trim below at the base, or will I hurt the plant? I ...
view the full question and answer
Non-native Japanese maple for East Northport NY
August 20, 2013 - I live in NY and I am looking to plant a Japanese maple in front of my house. It would be in front of a window so I'm thinking should I get a dwarf? Or a semi dwarf? I know I want a red color but un...
view the full question and answer
Dwarf evergreen heath plant from Norcross GA
February 01, 2010 - I was reading a book that mentioned a "dwarf evergreen heath plant and wondered if such a plant exist. It is suppose to have leathery leave blooms with white flowers that produce red berries used fo...
view the full question and answer
Non-native, invasive King Ranch bluestem and Coastal bermuda for horses
April 02, 2008 - Is blue stem grass mixed with coastal good for horses?
view the full question and answer
Support the Wildflower Center by Donating Online or Becoming a Member today. |