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 Erosion Control Questions

Plants to stop erosion on sandy slope in north central Texas
November 27, 2009 - We have severe erosion problems that lead to a deep ravine. There are deer in the area and the soil is sandy on a slope. What would be the best long term solution to stop or control this erosion. Th...
view the full question and answer

Plants for slope on Orcas Island, WA
July 21, 2011 - Hi! What a great site! Okay, I have a home on Orcas Island, WA. We live here from about June through September, but only visit once a month or so the other times of the year. We are looking for somet...
view the full question and answer

Plants for erosion control on steep bank in Ohio
June 10, 2008 - Another erosion question: We bought a place a year and a half ago with a stream/road run off at the back of our property. The southern exposure bank is quite high, I'm guessing 12 feet and therefor...
view the full question and answer

Salt tolerant plants for shade on tidal inlet in NY
August 11, 2013 - Are there any salt water tolerant grasses or forbs with deep roots that grow in shade? I live on a tidal inlet/canal on Long Island NY. The southern bank has cedars and oaks but the soil is eroding ...
view the full question and answer

Plants to stabilize a bank in VT
April 10, 2012 - I am looking for suggestion on what plants might best be suited for aiding in the stabilization of a very steep bank above Lake Champlain.
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