En Español

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

Please forgive us, but Mr. Smarty Plants has been overwhelmed by a flood of mail and must take a break for awhile to catch up. We hope to be accepting new questions again soon. Thank you!

Need help with plant identification, visit the plant identification page.

rate this answer
Not Yet Rated

Wednesday - November 13, 2013

From: Rockville, MD
Region: Mid-Atlantic
Topic: Diseases and Disorders, Seasonal Tasks, Wildflowers
Title: Cutting Back Perennials in the Fall?
Answered by: Anne Van Nest


We have large beds of flowering native perennials that we planted around our house as part of a landscape conservation plan (various Joe-Pyes, goldenrods, turtlehead, blazing star, brown-eyed Susans). Fall is upon us in Montgomery County, MD, and we see lots of birds having a great time kicking around in the leaves from the trees that are littering the beds. In the past we've cleaned the beds out down to the mulch layer before winter, but I'm starting to wonder if this is best for the plants and animals. Do we have to clean out the tree leaves before winter to keep the plants healthy? Can we leave them, or will this promote too much disease?


The only parts of the garden that really need to be cleaned up well (down to the mulch or even replace this too) are any area around a seriously diseased plant. While native plants are generally disease and pest free, some problems like powdery mildew on phlox, leaf spot on bugbane, or overwintering leafminer on gaillardia could be serious enough to harm the plants. In this case all the affected foliage should be removed so that the fungus spores or insect eggs and pupa do not overwinter.  For the rest of the garden, healthy woody perennials can often be left intact or pruned to 6 inches for the winter.  Any seeds or insects still on the plant will be welcome food for the wildlife and the uncut stems will help collect insulating snow around the plant and give it extra protection as well as mark where the plants are located next spring.
Any fleshy perennials though (like touch-me-nots) should be removed in the fall since they will turn into a mushy mess after the first frost.
Leonard Perry of The University of Vermont Extension has posted a good information sheet on Fall Perennial Care online.


From the Image Gallery

Joe-pye weed
Eupatoriadelphus maculatus

Ohio goldenrod
Oligoneuron ohioense

Pink turtlehead
Chelone lyonii

Ontario blazing star
Liatris cylindracea

Black-eyed susan
Rudbeckia hirta

Fall phlox
Phlox paniculata

Indian blanket
Gaillardia pulchella

Impatiens capensis

More Diseases and Disorders Questions

Leaves browning on non-native willow from in Cumbla PA
July 10, 2011 - We recently planted a willow tree. A lot of the leaves turned yellow and some turned brown, but it is also getting some new buds. my question is, should I take the dead leaves off or leave them there...
view the full question and answer

Problems with maple in Denver
June 09, 2011 - I live in Denver, CO and planted an Autumn Blaze maple three years ago. It has done very well until about a week ago. The leaves are drying out and falling off and earlier today I noticed some bugs ...
view the full question and answer

Diagnosis of problems with Texas ash
June 07, 2006 - Our 15 year old Texas ash has less leaf production this year. It also has a small amount of algae on the trunk, and some of the branches have small white spots on it. Also, a few of the branches close...
view the full question and answer

Loss of leaves from globe willows in Utah
July 26, 2008 - I have four globe willows that have been in my back yard for the past 6 years. For the past month they have been losing their leaves from the bottom up. We had aphids in some of our other trees and ...
view the full question and answer

Stress on Goldenball leadtrees from Austin
June 07, 2014 - I know of two separate instances where young Goldenball Lead Trees (leucena retusa) have shown symptoms of defoliation and a bleeding of white sap from sores that have developed on the bark. The first...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
© 2016 Lady Bird Johnson Wildflower Center