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?

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
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
1 rating

Saturday - March 03, 2007

From: Tyler, TX
Region: Southwest
Topic: Best of Smarty, General Botany, Poisonous Plants
Title: Native plants that will grow under alleopathic black walnut
Answered by: Nan Hampton

QUESTION:

I have a large, beautiful black walnut tree in my yard and have trouble growing the annuals, begonia, impatients, etc., that I have always grown. They don't do well in the ground and I have resorted to putting them in pots in order to have some color in that shady area. Any suggestions as to what soil amendment I can use so they can be planted in the ground?

ANSWER:

Your black walnut tree (Juglans nigra) is defending its space—that's why you are having trouble getting any other plants to grow underneath it. With this defense mechanism, called allelopathy, the tree makes and releases a chemical called juglone that adversely affects many other (but not all) plants. Juglone can be found in all parts of the black walnut tree. If the roots of another plant come within 1/2 inch of the walnuts roots, they can absorb the juglone and sicken and die. Also, walnut leaf litter and walnut fruit on the ground leach juglone into the soil.

Virginia Extension Service has an excellent discussion of the black walnut and its allelopathic effects. Additionally, the article lists common plants that are affected by the juglone of the walnut. There is also a list of plants that will grow near the black walnut. Here are a few attractive native plants that will grow underneath your tree in Tyler:

Black-eyed susan (Rudbeckia hirta)
Pink evening primrose (Oenothera speciosa)
Cardinal flower (Lobelia cardinalis)
Virginia creeper (Parthenocissus quinquefolia)
Inland sea oats (Chasmanthium latifolium)

By the way, allelopathy is one of the reasons some invasive plants, such as spotted knapweed (Centaurea biebersteinii), are so successful.

 

More Poisonous Plants Questions

Is the fruit of Melothria pendula edible?
November 22, 2014 - Is the fruit of Melothria pendula edible?
view the full question and answer

Could ammonia harm poisonous, non-native oleander in Bay Point CA
December 20, 2009 - Could ammonia harm my Oleander plant? I have been spraying ammonia under it to keep neighborhood cats from using the soil under the plant as a sand box. If so, do you have any suggestions as to what...
view the full question and answer

Rash resulting from cutting trees in NC.
May 08, 2012 - My boyfriend was cutting some trees yesterday. He had thorns in his hands after he was done, and today he has a rash on his legs, a fever and he feels like throwing up. Can you tell me if its symptoms...
view the full question and answer

Precautions to take with Jack-in-the-Pulpit, Arisaema triphyllum
September 13, 2009 - Are there precautions to take, such as wearing gloves while separating the seeds from the Jack In The Pulpit berries. The photos I have seen have gloved hands. I've read that the plant is toxic if in...
view the full question and answer

Recommended plants for horse farm in Lansford PA
April 22, 2010 - Recently started a small horse farm in northeast Pennsylvania just east of the Pocono Mountain plateau. Located in a foggy valley adjacent to a lake. Snowy, cold winters; wet springs; dry summers; ni...
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.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | SITEMAP
© 2014 Lady Bird Johnson Wildflower Center