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

Thursday - June 20, 2013

From: Buckley, WA
Region: Northwest
Topic: Pests, Shrubs
Title: Spots on calycanthus petals from Buckley WA
Answered by: Barbara Medford


Petals on calycanthus develop black spots the turn into holes. Problem appears shortly after buds open. Occurs every year. Foliage is healthy. Plant growing well and doubles or triples size every year. Has been in present location about four years.


There are two members of the Calycanthus genus native to North America. This USDA Plant Profile of Calycanthus floridus (Eastern sweetshrub) shows it growing nowhere in western North America. According to our webpage on Calycanthus occidentalis (Western sweetshrub) it is endemic to California. The USDA Plant Profile shows it growing only in Klickitat County of Washington, a couple counties away from you in Pierce Co., but we assume the climate, rainfall and soils are nearly enough alike that it will do all right in your garden.

From our webpage, here are the growing conditions for Calycanthus occidentalis (Western sweetshrub):

"Growing Conditions

Light Requirement: Sun , Part Shade
Soil Moisture: Moist
Soil Description: Moist soils.
Conditions Comments: Calycanthus occidentalis will develop leaf burn if planting site is too dry."

Please note the comment on leaf burn, if the site is too dry, as well as the need for sun (6 hours or more of sun a day) or part shade (2 to 6 hours of sun), but that is referring to leaves, and we assume you are finding the spots on the petals of the flowers. So, we will look further and see if we can find an explanation of the spots on blossoms.

Here is more information and pictures from Las Pilitas Nursery in California. From that, we learned that pollination is by members of the Nitidulidae family of beetles. Further research said that these are sap sucking beetles, and we could not find any indication that they did damage to flowers they were pollinating.

All the references we searched said that the plant was relatively pest and disease free. Since, as you say, the plants are healthy, we would not be too worried about it. We are native plant gardeners, not entomologists, but if you are concerned, you might contact the Washington State University Extension Office for Pierce County to see if other similar occurrences have been reported in your area.


From the Image Gallery

Western sweetshrub
Calycanthus occidentalis

More Shrubs Questions

Plant identification for shrub in Florida
September 03, 2011 - On our street we have ornamental shrub planted in the median that has small waxy green leaves, produces small fragrant white flowers, and red berries with white pulp and small seeds on the inside. Th...
view the full question and answer

Hedge border for Boynton Beach FL
September 21, 2009 - Seek recommendations for planting in zip code 33437: 2-2.5' high, dense formal hedge border: minimal care, full sun, sandy, 1-2x/wk irrigation. Is Ficus Green Island Microcarpa suitable? Other rec...
view the full question and answer

How to germinate seed for Styrax grandifolius
October 18, 2014 - How do I germinate seed for the Styrax grandifolius?
view the full question and answer

Transplanting adventitious shoots of a mountain laurel in San Antonio
August 20, 2009 - Is it possible to transplant branches (shoots) growing from a mountain laurel that was chopped down? Some are two years old and several feet tall (but not yet blooming) and some as small as a foot. ...
view the full question and answer

Wintering a Lemon Cypress tree in Eagan MN
September 29, 2009 - I Have a 2 1/2' Lemon Cypress Tree. I'm wondering if I can leave it outdoors for the winter, if not, how would I winter over indoors?
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