Explore Plants

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
    
 

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 Best of Smarty Questions

Is there an automated image download function for the NPIN Image Gallery?
November 03, 2009 - Hi, I have a database/web technical question. Do you provide an interface to retrieve photos from your website programatically? Thanks!
view the full question and answer

Mixture of native grasses as opposed to buffalo grass monoculture
November 26, 2003 - My husband and I just built our home on Lake Travis. Our lot is very rocky and is on the side of a hill. We would like to plant something on the incline at the front of our home that doesn't need a l...
view the full question and answer

Growing Native Plants in Juniper litter from Wimberley, TX
October 04, 2010 - Junipers create an environment under their canopy that prohibits growth of other plants. I have a virgin lot that has been cleared of many juniper but has remaining heavy natural leaf mold containing...
view the full question and answer

Is there a flower that blooms only once in seven years?
December 17, 2008 - Just wanted to know if there exists a flower that blooms only once in seven years? Thank you!
view the full question and answer

Need bug repelling plants in Arlington, VA
February 08, 2010 - What kind of plants are best bug repellents, and need little or no maintenance. I'm a city girl and don't like bugs (spiders)
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.