En EspaŅol
Share

Ask Mr. Smarty Plants

Mr. Smarty Plants - Failure to thrive of Magnolia grandiflora in Las Vegas NV

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

QUESTION:

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.

ANSWER:

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

Small tree to plant with high bush blueberry plants
May 13, 2008 - Dear Mr. Smarty Plants, I have four wonderful new highbush blueberry plants. I like to plant a native tree nearby to accent them, but cannot find a suitable one. I'd like a tree that is not going ...
view the full question and answer

Will arctostaphylos grow in Austin, from Murrieta CA
April 23, 2013 - I currently live in Murrieta, CA at 2,000 ft. We planted 800 native plants on our slopes so they were extremely drought tolerant. One of my favorites is the Arctostaphylos family that will take the fr...
view the full question and answer

Lighting for the Wildflower Center from Austin
December 16, 2012 - Hello Mr Smarty, On a recent night trip to the Center, there was an oak that was beautifully lit for the holidays. It seemed to come from one ground light, but cast hundreds of glistening "stars"...
view the full question and answer

Growing Chilopsis in Florida
July 25, 2013 - I live in St. Johns County, FL between Jacksonville and St Augustine. I live inland, not near the beach. I bought a small desert willow plant in Victoria, TX and brought it back to FL to grow. I plan ...
view the full question and answer

Privacy hedge for South Dakota
August 08, 2008 - Hi, I'm looking for something to use as a hedge. 8 foot or so tall offering semi privacy all year. I like dogwoods but loss of leaves in the winter makes me skeptical. Boxwood would be interesting...
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
© 2014 Lady Bird Johnson Wildflower Center