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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.

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Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

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Tuesday - June 07, 2011

From: Chandler, AZ
Region: Southwest
Topic: Diseases and Disorders, Watering, Shrubs, Trees
Title: Mountain Laurel having trouble in AZ
Answered by: Brigid & Larry Larson

QUESTION:

A Sophora secundflora (Texas mountain laurel) was planted to an Arizona north faced front yard last year in August under full sun. Starting early this year, I noticed its leaves turn to light green and the flowers become pale purple/white. I water it 30 mins a day. What could be its problem? Please help this beautiful tree, thanks!

ANSWER:

Mr Smarty Plants thinks its likely that you are taking way too much care of your Sophora secundiflora (Texas mountain laurel).  Ours (in Austin) simply lives in the front yard, we enjoy its blooms and fragrance but give it no care at all. Once the plant is established, you do not not need to water, unless in extreme drought.  You need to stop watering it everyday. If you must, give it a long slow soaking once a month.  The mountain laurels that are seen in the Texas hill country are also understory plants, so they will thrive with some shade.  Arizona is a bit farther into the desert southwest than it's preferred native conditions, but not that far.  This link is to the USDA database showing where it thrives.  If you click on the states, it will show county level detail.

Reviewing the NPIN profile for the Texas mountain laurel, it emphasizes again that it's water use is "Low to Medium" and that it prefers "Dry, rocky, well-drained, preferably calcareous soils". The need for good drainage is emphasized.

Transplant shock is also a possble cause.  Here is a recent MSP question that also considers that issue.

 

From the Image Gallery


Texas mountain laurel
Sophora secundiflora

Texas mountain laurel
Sophora secundiflora

Texas mountain laurel
Sophora secundiflora

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