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
Not Yet Rated

Tuesday - September 04, 2012

From: Austin, TX
Region: Southwest
Topic: Problem Plants, Erosion Control
Title: Exposed Tree Roots in Austin
Answered by: Brigid & Larry Larson

QUESTION:

I have a large ash tree with a lot of mud at the top of a sloping yard. I want to build a small retaining wall with the ground leveled above. This would entail covering exposed tree roots with 4-18 inches of dirt. Will this hurt the tree?

ANSWER:

Mr Smarty Plants is a bit mixed on your question.  Common knowledge has it that it is harmful to a tree to cover its roots,  yet if the roots are exposed anyway it is tempting to cover them a bit.

  This article from the Colorado Extension describes the root mass,  both that it extends beyond the tree crown and that the majority of the action is within 6 to 24” of the surface.

  The issue with covering the roots involves compaction of the soil.  The article above states  ”Changes in soil depth around trees can also cause injury to root systems.  The addition of only 4 to 6 inches of soil over a root zone drastically reduces the amount of oxygen and water available to the roots”

  A great solution to your desire is to build a “Tree Well”, where the roots are covered with very coarse rock or mulch to preserve their air and water access.  This publication from the West Virginia Extension states 18” as the depth where plain dirt fill would be too deep.  It gives excellent recommendations on building a tree well.

 

From the Image Gallery


Green ash
Fraxinus pennsylvanica

Texas ash
Fraxinus albicans

Arizona ash
Fraxinus velutina

More Problem Plants Questions

Zinc tolerant plants for sunny area
June 08, 2012 - I have a very high zinc soil in an all day sun area. Any suggestions as to what kind of flower can I grow successfully? Zone 8 Thank you
view the full question and answer

Giant Thistle-Like Plant from Elgin, TX
June 01, 2014 - I have a giant thistle like plant in my field we have been unable to identify. It looks like a milk thistle but it is short..only about a foot tall..stocky...and the flowers are giant..about 6 to 8 i...
view the full question and answer

Live oak sprouts in Austin
August 01, 2010 - How can I control the hundreds of live oak sprouts our lovely trees are throwing off? We recently landscaped with rain gardens and the related drainage ditches; they are filled with these very happy ...
view the full question and answer

Elimination of Whitemouth dayflower in Dothan AL
March 18, 2009 - I am infested with Widow's Tears in my yard. I would like to get rid of them. Can you tell me how?
view the full question and answer

Shoots sprouting around base of liveoak tree
April 18, 2008 - I have a Live Oak that was planted in my yard about 15 years ago. In the last several years, small shoots have been sprouting up around the tree base, are getting more dense and spreading into the gr...
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 | STAFF
© 2015 Lady Bird Johnson Wildflower Center