Homeowner?s Crusade against the Invasive Japanese Knotweed

Kathy and Edmund Olson recently purchased their home with a natural wooded landscape in Downers Grove when I first visited their property.  They asked me to I.D. some native plants, certify their yard for Conservation@Home and give suggestions on what they could do about the large amount of invasive Japanese Knotweed along the back border of their property, adjacent to St. Joseph’s Creek. Management of invasive plants is one of the requirements of the Conservation@Home program. Invasive plants choke out our native plant species and the benefits they provide, spread easily from our yards to natural areas, and cost millions of dollars to eradicate. To learn more about invasive plants:

 Invasive Plant Factsheet

 Japanese Knotweed is a 12 foot tall perennial with 4-6” alternating leaves, hollow reddish or spotted zigzag stems, and drooping green to white spikes of fragrant flowers in late summer.  It resembles a shrub, often grows near waterways, where seeds and roots can be easily transported, and is highly rhizomatous.  To learn more about this plant:

Japanese Knotweed Factsheet


Japanese Knotweed in the Olson’s backyard along St. Joseph Creek


I could tell they felt a little overwhelmed, understandably, with the task of removing so much Japanese Knotweed. Just a small piece of root left in the soil can easily re-sprout.  I suggested they hire a professional who knows how to correctly herbicide this species along waterways.  They were concerned about the costs, but I explained the upfront costs of hiring the right professional will save them money and time in the long run, plus it would be almost impossible to dig out.  I also recommended they work with their neighbors and the city to try to form a partnership with the company they hire to educate and eradicate this aggressive invasive in other places and reduce the chance of it returning onto their property.  Here is my interview with them describing accomplishments, steps taken, and lessons learned to help others tackle invasive plants in their landscapes and community.


What key steps did you take to tackle the Japanese Knotweed in your landscape?

Kathy and Edmund: We first cleaned up the area from by cutting the knotweeds stalks and piling them to decompose. We had to be careful that the cuttings did not re-root themselves. It was hard work but made me feel so much better to see the stalks gone. It is such a tall plant and it just keeps creeping closer and closer to the house. I had nightmares about it. Then we had it treated in the spring when it was a few feet tall by professionals. That first treatment worked very well, and pushed back the infestation tremendously. They did such a careful job that the native plants were not killed, just the knotweed.


What partnerships did you form and how did they help?

Kathy and Edmund: After getting information about how to start working on this problem with Denise Sandoval from The Conservation Foundation, we called the company Tallgrass Restoration and worked with them to start a plan to eradicate the knotweed. Then I called Northern Illinois Invasive Plant Partnership (NIIPP) and talked with Cathy McGlynn to report the invasive plant. She organized a meeting for me with folks who have this problem in the area: the Dupage Forest Preserve and Downers Grove Park district. They worked on their land as we were working on our land. Later she sent out flyers to all the homeowners along St. Joseph Creek and educated some village officials of the problem. Working together we were able to start controlling this dreadful weed on various properties. The last treatment on our property was paid for by a grant from the NIIPP.


What do you have left to do?

Kathy and Edmund: We still need some very light control in a few stubborn spots but we have very few knotweed plants. We have planted some oaks and shrubs. I can’t wait to see them take off. I’m working on getting some more beneficial native plants in there too. It has taken three years to be rid (mostly) of the knotweed. Now we need to make sure it doesn’t come back.


After you’ve been through this experience, is there anything you would do differently regarding Japanese Knotweed or in general?

Kathy and Edmund: It seemed to me that everything fell into place. I was very fortunate that the timing was right to talk about this plant and that people were willing to listen. This plant is now on the invasive plant list so that the organization NIIPP was there to help as well as the land restoration knowledge.


Any advice or useful sources of information you’d like to share?

Kathy and Edmund: The Internet is a good place to gather information. When I first found out what we had growing on our new property, I was upset. But I found out that they have ways of controlling it. Be assured that it takes a few years for really large infestation like ours. And definitely talk to folks who know about plants, like The Conservation Foundation, Greater DuPage Wild Ones and even your Forest Preserve.


What should others do if they spot invasive species in other areas?

Kathy and Edmund: If you spot Invasive species you should report it to the website…

Cathy McGlynn, Coordinator
Northeast Illinois Invasive Plant Partnership
c/o Chicago Botanic Garden
1000 Lake Cook Road | Glencoe, IL 60022
Office 847-242-6423 | Mobile 845-667-4981| Fax 847-242-6330


Since our first meeting, Kathy and Edmund have removed other invasive plants from their landscape like Garlic Mustard, Buckthorn, Japanese Honeysuckle. “Denise showed us what Dames Rocket looked like, and we  have been working on that too.“  They also planted more native plants, continue to be active in several environmental organizations such as The Conservation Foundation  and continue to work in their community.

Denise Sandoval Conservation@Home assistant, dsandoval@theconservationfoundation.org

Like this article? Share it!

Share on facebook
Share on Facebook
Share on twitter
Share on Twitter
Share on linkedin
Share on Linkdin
Share on pinterest
Share on Pinterest