En Español

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

Saturday - March 24, 2012

From: Rio Grande City, TX
Region: Southwest
Topic: Planting, Trees
Title: Trees safe near walls from Rio Grande City
Answered by: Barbara Medford

QUESTION:

What trees can be planted near the house that the roots won't break my walls?

ANSWER:

It's not so much what trees, as how close you want to get the tree to the wall. Actually, what you are concerned with is that the roots will break the walls. What happens is that a tree root system, often up to 3 times the width of the upper crown of the tree, is constantly searching for water, especially during dry times of the year. Those roots, moving unseen  beneath your soil, when they encounter a cement foundation, will very resourcefully dip down beneath the concrete, slurp water up out of the soil. The soil will then shrink, which removes the support from your concrete base, which then cracks. If it cracks, the walls supported by the foundation will begin to sink, get out of plumb and, yes, crack. Most tree roots are in the top 12" or so of the ground, and they actively will compete for water from that soil. Some trees, like Liquidambar styraciflua (Sweetgum) and members of the Acer (maple) genus have roots that rise to the surface to improve their access to moisture and oxygen.

This article from the Morton Arboretum Tree Roots and Foundation Damage explains the problem far better than we can. The main point of the article is that the tree roots didn't start out to destroy your foundation; it started out looking for water. When the roots came to your foundation, they dipped down below the house looking for moisture. Having found it, they have a nice drink, pulling water out of the soil, and causing the soil to subside. The soil, which is the support for your house, started shrinking and, without that support, the cement started cracking.

A tree that grows very tall is going to need lots of space under ground (and not very far down from the surface) to gather sufficient nutrients from the soil, storing water and, perhaps most importantly, anchoring that tree in the ground. You have heard the expression "top-heavy" we are sure; apply that to a large tree and you can perhaps visualize a tree that topples in a wind or even if someone leans against it. And with an instinct for survival, tree roots stand up for themselves, or perhaps we should say "push up" because they will push up sidewalks and driveways, as well as crack foundations in search of water.Remember that roots are radiating out in all direction from that trunk for as much as 2 to 3 times the width of of the top of the tree.

The time to deal with the problem of roots getting into foundations is to address the problem before you ever select or plant a tree. An itty-bitty oak planted next winter (you know we only recommend planting trees in December and January, when they are dormant, don't you?) can easily be fitted into a space maybe 6 ft. from the foundation. A great big shade tree will have roots radiating under it for many more feet than the size of the visible crown of the tree. The upper branches will be trying to get in the windows of your house and assisting termites and rats to access the roof of your house and entrance to your attic. The main thing to remember is that a small newly-planted tree can do two things: grow or die.

 

More Trees Questions

How many native trees in U.S. from Clarkson MI
May 18, 2011 - Does anybody have any numbers on how many native trees there are in the entire United States?
view the full question and answer

Caterpillars on Mountain laurel in Austin
September 11, 2009 - One of our 18+ year old Texas Mountain Laurels seems to be in distress this year. We treated it for caterpillars this Spring but many of the new leaves had been eaten by then. I recently started wate...
view the full question and answer

Texas wild olive for Summerfield FL
January 17, 2013 - I want to buy a Texas Wild Olive for my home in Summerfield, Fl. My landscaper brought me a regular olive tree saying he had never heard of a Texas Olive Tree in our area. I have looked on line withou...
view the full question and answer

Need help with pruning my Anacacho Orchid tree.
January 04, 2010 - We have an Anacacho Orchid Tree which has done so well in its location that we will need to prune it back. Please advise how much we can prune it and what time of year to do so. Thank you
view the full question and answer

Safe branch length of oaks in Clayton NC
November 06, 2011 - I have 2 very large oak trees in my yard and I am concerned about the length of the branches over the house and driveway. Most seem larger than 4" in diameter. What is a safe length for these branc...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | JOBS | SITEMAP | STAFF INTRANET
© 2016 Lady Bird Johnson Wildflower Center