Rent Shop Volunteer Join

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
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 General Botany Questions

Difference between Styrax platanifolius and Styrax patanifolius ssp. texanus
November 18, 2011 - What is the difference between a Styrax platanifolius and a Styrax platanifolius texanus?
view the full question and answer

What to do about grass dying under pin oaks in Iowa
December 10, 2008 - We have 2 pin oaks about 15 years old in our front yard. The grass has started dying out under and around them. What can we do?
view the full question and answer

Where do snake herb and skeleton-leaf goldeneye get their names?
October 05, 2014 - Dear Mr. Smarty Plants, Where does snake herb, and skeleton leaf goldeneye get their names from? Thank you.
view the full question and answer

Does music affect sunflower growth from Pentwater MI
January 12, 2010 - Does music affect sunflower growth?
view the full question and answer

How do plants living in various climates differ?
February 25, 2008 - Do plants that live in different climates have different tecture or are they just totally different?
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.