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?


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

Sunday - May 04, 2014

From: Benson, AZ
Region: Southwest
Topic: Soils, Shrubs
Title: Chlorotic Texas Mountain Laurel in Benson, Arizona
Answered by: Jimmy Mills


I've planted a Texas Mountain Laurel in heavy clay soil in Arizona. It's been in place for 3 years and flowers each spring. However it's leaves are a shade of medium, yellowish green nothing like the dark green of the mountain laurel trees around Tucson. I'm 40 miles east of Tucson at 4000' elevation. Is there something I need to do to improve it's condition? Thank you.


This quote from the NPIN page for Texas Mountain  Laurel Sophora secundiflora (Texas mountain laurel) may give us a clue  about the problem you are facing: “Sophora secundiflora is very popular as a native evergreen ornamental tree within its range, valued for its handsome, dark green foliage and lush early spring blooms.”  This USDA distribution map shows us that  Arizona is not in its range.

Also from its NPIN  page, the Growing Conditions provides useful information.

Growing Conditions

Water Use: Low , Medium
Light Requirement: Sun , Part Shade
Soil Moisture: Dry , Moist
Soil pH: Alkaline (pH>7.2)
CaCO3 Tolerance: High
Drought Tolerance: High
Cold Tolerant: yes
Heat Tolerant: yes
Soil Description: Dry, rocky, well-drained, preferably calcareous soils. Sandy, Sandy Loam, Medium Loam, Clay Loam, Clay
Conditions Comments: Needs good drainage.

Your description of the problem that your Texas Mountain Laurel is having sounds like chlorosis, which can have several causes. Mostly likely in this case, the heavy clay is not providing good drainage which in turn is limiting the availability of iron to the plant. Iron is important in the pathway that allows the plant to produce chlorophyll. Low iron = low chlorophyll = yellow leaves.
I’m including links describing chlorosis, and tips for working with clay soils.

  iron chlorosis

  ammending clay soils

  improoving clay soils

For some help closer to home, you might want to contact the folks at the Cochise County office of the University of Arizona Extension Service .


From the Image Gallery

Texas mountain laurel
Sophora secundiflora

More Soils Questions

Coffee grounds as mulch into vegetable beds
February 05, 2009 - Can you put too much coffee grounds as mulch into vegetable beds?
view the full question and answer

Native plants for poorly drained clay soil
March 24, 2008 - I am trying to establish a native plant garden in my back yard, I have two places where water stands for a few hours after a heavy rain, and the soil is black clay. Can you recommend any perennials 3...
view the full question and answer

Plants for steep slope in Pittsburgh PA
April 25, 2013 - I have a similar question to one from SC. I live in Pittsburgh, PA. We have a steep slope behind a newly built in pool. What type of plants can I put on the hillside to hold the soil. It gets a ...
view the full question and answer

Shriveling agave from Miami Florida
August 23, 2013 - Dear Mr. Smarty Plants, Most upset - My beautiful agave (wish I could have submitted an image) has stared to misbehave. The once first liquid filled leaves, are starting to look more like the skin ...
view the full question and answer

Brown leaves on Burr Oak from Dripping Springs TX
October 05, 2013 - We have recently planted a 15 gal. burr oak in an correct hole with great soil and plenty of watering in. We have noticed some brown leaves. Should we be worried?
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
© 2016 Lady Bird Johnson Wildflower Center