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
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

Plants to replace Phragmites australis (Common reed) in Cedar Ridge Preserve
February 25, 2015 - Dear Mr. Smarty Plants, I live in the DFW area and volunteer at a preserve (Cedar Ridge). We are constantly battling the common reed, Phragmites australis, around the pond. I am wondering what shou...
view the full question and answer

removing paper mulberry shoots from lawn
August 09, 2011 - Dear Mr./Ms. Smartypants, I recently moved into an Austin home with the backyard taken over by paper mulberries. There were originally 2-3 large bush/trees, but now that I've removed them I realiz...
view the full question and answer

Eliminating bluebonnets from lawn
December 05, 2009 - I need to know the best way to eliminate bluebonnets which are growing in my yard. My HOA is pursuing legal action against me to prevent me growing the plants. I can't afford to "resod" my yard. Ca...
view the full question and answer

Should a tree near a water well be transplanted?
July 31, 2013 - I have a water well and have about a 6 yr live oak planted in close proximity to it( about 10 feet). Would it be wise enough to transplant the tree while its this young or leave it alone. Also I need ...
view the full question and answer

Eliminating unwanted vine on arbor in San Francisco
November 20, 2012 - There is a vine growing on our arbor, it has sickle-shaped pods and is crushing the arbor, how do we get rid of it?
view the full question and answer

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