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?

Share

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
3 ratings

Monday - July 28, 2008

From: Washington, CT
Region: Northeast
Topic: Invasive Plants, Problem Plants
Title: How to get rid of Japanese knotweed (Polygonum cuspidatum)
Answered by: Nan Hampton

QUESTION:

We have an enormous stand of japanese polygonum that we are trying to get rid of. What soil type is the most inhospitable to this aggressive and highly invasive species? Were thinking of planting some native white pines in the area to grow over them as well as manually digging them out. What would you suggest? Thanks.

ANSWER:

Polygonum cuspidatum (Japanese knotweed) is on the Least Wanted list of the Plant Conservation Alliance's Alien Plant Working Group. It appears from their description that nothing is inhospitable to this plant. As their web site states: "Japanese knotweed can tolerate a variety of adverse conditions including full shade, high temperatures, high salinity, and drought." Planting Pinus strobus (eastern white pine) over the area where the Japanese knotweed grows is a very nice idea, but it won't affect the status of the knotweed. Digging them out is the most environmentally friendly way to get rid of them; and, depending on the size of your population, it might be the best way to eliminate your plants.  The Plant Conservation Alliance also gives specific instructions on chemical treatment for large or difficult populations. The Nature Conservancy and Clark County, Washington also have information on control programs and their success.

 

 

More Invasive Plants Questions

Where is marijuana plant native?
April 03, 2005 - In what part of the world is the marijuana plant native?
view the full question and answer

Removal of non-native invasive Ligustrum japonica from Austin
February 14, 2012 - I bought a house that I am slowly turning into a native garden, but as a teacher, I have a really small budget. One entire border of my backyard (30 feet) was planted with evil Ligustrum japonica. I l...
view the full question and answer

What to do about bastard cabbage in the Austin area?
May 08, 2015 - I am noticing bastard cabbage taking over roadsides and medians at an alarming rate where a mixture of native flowers used to bloom. Is it allowable to organize efforts to pull the invasive plants ou...
view the full question and answer

Type of clumping bamboo for outdoor planters from Plano TX
March 25, 2014 - What type of clumping bamboo can be grown outdoors in planters in Dallas,TX?
view the full question and answer

Removal of non-native zoysia grass from Burgettstown PA
September 12, 2013 - What is the most effective method of killing zoysia grass? We bought a house that sits in the center of four acres of mature zoysia. It looks beautiful, however, despite our best efforts at "weeding...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | JOBS | SITEMAP | STAFF INTRANET
© 2016 Lady Bird Johnson Wildflower Center