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?


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
1 rating

Monday - January 17, 2011

From: Las Vegas, NV
Region: Rocky Mountain
Topic: Trees
Title: Failure to thrive of Magnolia grandiflora in Las Vegas NV
Answered by: Barbara Medford


I live in Las Vegas, NV and have several Magnolia Grandiflora trees. They were doing well until 2 years ago when they started losing their leaves. The leaves turn brown or very dark on the edges. One landscaper said they need Sulfur from the local nursery. Didn't seem to help. One said more water. Helped for a short time, deep root watering. Any nutrients or minerals I can use to help them. The flowers are gorgeous and I hate to lose them.


As you will note from this USDA Plant Profile map, Magnolia grandiflora (Southern magnolia) does not grow natively anywhere west of Texas, and East Texas, at that. In part, the accuracy of our answer depends on how recently those trees were planted. If you planted them three years ago, and they started losing their leaves 2 years ago, then we expect that when the tree roots got out of the good dirt you probably planted them in, those roots could not tolerate the soil they found themselves in. If they were planted several years ago, then we are astounded they lasted that long. Take a look at the Growing Conditions from the page in our Plant Database for this tree:

"Growing Conditions

Water Use: High
Light Requirement: Part Shade
Soil Moisture: Dry
CaCO3 Tolerance: Low
Cold Tolerant: yes
Soil Description: Rich, porous, acid soils. Sandy, Sandy Loam, Medium Loam, Clay Loam Clay, Acid-based, Calcareous

Also, from that same page, here are the normal habitats of this tree: "Native Distribution: Coastal Plain from extreme s.e. VA to FL, w. to e. TX."

Doesn't sound a whole lot like Nevada, does it? We're betting that you have alkaline soil, with a Ph above 7, as does most of the western United States. Magnolias need acid soils, as noted above, with a Ph below 7. The sulfur recommended was probably an attempt to help in that situation. But that magnolia tree ordinarily would grow very large, with underground roots to match or exceed the circumference of the top. See this article from Utah State University Extension on soil alkalinity to get a better idea of the problem. If that proves to be the case, it demonstrates again the desirability of using plants native to the area in which you are trying to grow them, which is the goal of the Lady Bird Johnson Wildflower Center. The magnolia has adapted to growing on forest floors, with a rich humus of centuries of fallen leaves beneath them, in part shade and with plenty of moisture.

Las Vegas is in USDA Plant Hardiness Zones ranging from 8a to 9b, and is in the arid Mohave Desert. We can understand your desire for a lovely evergreen tree with big white flowers, but in view of the environmental situation there, where more xeriscapes are being encouraged, a woodland native like the magnolia is not a good choice. We suggest that you contact the University of Nevada Extension Office for Clark County to see what their take on your problem is.




More Trees Questions

Climbing options for a Coral honeysuckle in Austin Texas
April 16, 2013 - Regarding Coral honeysuckle, what is the best support to encourage continued spread, chicken-wire/fencing? Currently the plants and vines are on fencing and beginning to fold over. I'd like to add...
view the full question and answer

Fast-growing shade tree for Corona CA
September 17, 2014 - Hi, I'm looking for a fast growing shade tree. I live in Corona CA so it will need to do well in a lot of sun, moderate winds and clay soil. Thanks so much for your suggestions.
view the full question and answer

Leaves turning yellow on Banana Shrub in Eutaw. AL
July 28, 2013 - We have a very large (about 12' tall), very old (probably planted in the early 1900s) Banana Shrub in our front yard. It was very healthy until last year when its leaves began turning yellow and fal...
view the full question and answer

Caterpillars ate my Sophora in La Mesa, CA.
July 06, 2011 - Before I noticed what was happening, my newly-planted 1 foot tall Sophora secundiflora was eaten by caterpillars. It now has no foliage. Do you think it will leaf out again?
view the full question and answer

Transplanting Magnolia grandiflora
June 11, 2007 - We just moved to Plano TX and there's a magnolia tree planted between our house and the driveway. (The tree is 7ft tall and it's about 7ft from the side of house and 4ft from the driveway) I alway...
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.
© 2015 Lady Bird Johnson Wildflower Center