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
3 ratings

Thursday - April 20, 2006

From: Kansas City, KS
Region: Midwest
Topic: Trees
Title: Inadvisability of mounding earth around tree in ring
Answered by: Joe Marcus

QUESTION:

We have a mimosa tree in our backyard. My husband wants to build a tree ring around it. My mother told me that some trees will die from having soil built up around it like that. Will a tree ring kill our mimosa tree?

ANSWER:

This is one of the more controversial topics in arboriculture. Some arborists swear by tree rings, others say they're useless and, worse, detrimental to the trees. I take a moderate stand on this. In my opinion, tree rings are useful for two purposes: providing a temporary aid to watering a tree after transplanting and protecting the crown of the tree from lawn equipment.

The old donut watering dike that we've all seen for many, many years has recently morphed into a mound of earth around the base of the tree. I have seen these as much as 1 foot in depth! These mounds do no good and actually can do great harm. Soil and mulch mounded against the trunk of a tree can harbor both harmful insects and pathogens and provide the perfect environment for them to gain entry to the base of a tree. Moreover, some trees seem to have some critical gas exchange happening at the base and certainly depend on oxygen at the roots. A thick mound of soil over the root ball greatly diminishes the volume of gases available that are critical to the health of the tree.

Watering rings (the donut mounds) should be built outside the hole dug for the tree, not on top of the root ball as they almost always are constructed. They're really not necessary if the tree owner will spend six minutes watering their newly transplanted tree at low flow rather than two minutes with the hose gushing at full pressure. Little sprinklers running at low pressure do a great job of watering new trees.

Some people maintain rings or bare earth or loose mulch around their trees as a way to protect them from mowers and weed trimmers. This is in general a good idea as mechanical damage to the base of a tree is often the source of serious problems far into the future. However, care should be exercised not to mound soil against the trunk of the tree or to smother the roots. For small trees, I like to use curved clay tiles or bricks as a physical barrier around the base of the tree. Grass can grow right up to (and into) the barrier which I can mow up to. If grass or weeds pop up between the barrier and the tree it's a simple matter to remove the tiles or bricks, pull or trim the grass and replace the barrier. If the barrier is not placed directly in contact with the base of the tree insects and diseases won't have any better chance of getting started than if it weren't there at all.

 

More Trees Questions

Trimming of Escarpment Oak from Austin
May 18, 2014 - We have a 2-year-old quercus fusiformis in our front yard and have been advised by some people that we need to remove the bottom branches and trim the ends of the branches that are hanging far down. ...
view the full question and answer

Texas smoketree
June 17, 2007 - Does a smoketree grow in Texas? How can I identify it?
view the full question and answer

Are baldcypress trees (Taxodium distichum) self-fertile
March 06, 2011 - We are considering planting a bald cypress in a grassy children's play area that has fair amount of clay in the soil and receives a good amount of rain water from an adjacent slope. This seems a good...
view the full question and answer

Protecting the Texas madrone from construction damage
January 11, 2010 - What is the best way to protect Texas Madrone trees (small, 8'-10') from damage during construction of a new home on a site with some single, some grouped Madrones?
view the full question and answer

Fenceline trees for Northwest Austin
January 14, 2011 - We live in Northwest Austin, near 183 and Anderson Mill. Our neighbor recently cut down all their trees in their backyard, which provided nice afternoon shade for us. We would like to re-plant some ...
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