Native Plants
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.
rate this answer
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 Problem Plants Questions
Eliminating evasive Celastrus orbiculatus (Oriental bittersweet)
July 21, 2013 - I have Oriental Bittersweet growing pervasively in my shrub garden, strangling my shrubs and growing into my beautiful Victorian porch. I can't keep up with it! What can I do?
view the full question and answer
More on bluebonnets
March 10, 2003 - Clover has taken over and just about covered the Bluebonnets. Is there any way of removing the clover such as with fertilizer or something else?
view the full question and answer
Controlling sedge in vegetable garden in Mississippi
August 03, 2008 - I have a veg. garden surrounded by Purple Sedge. The nut grass has been contained/eliminated by replacing all dirt 1' down. Now the surrounding sedge is beginning to creep inward infesting the gard...
view the full question and answer
Protecting storm-damaged pecan and black walnut trees in TX
June 29, 2015 - Several trees on our property in northeast Texas were uprooted by a tornado. A pecan tree with a circumference greater than 93 inches was carried to the ground. Although it is completely horizontal,...
view the full question and answer
Elimination of non-native, invasive King Ranch bluestem in lawn
June 06, 2006 - How can I eliminate an annual infestation of king ranch bluestem in my bermuda lawn?
Thanks.
view the full question and answer
Support the Wildflower Center by Donating Online or Becoming a Member today. |