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 - March 24, 2013

From: St. Augustine, FL
Region: Southeast
Topic: Invasive Plants, Non-Natives, Herbs/Forbs, Trees
Title: Will non-native and invasive Mexican petunias grow under oak trees from St. Augustine FL
Answered by: Barbara Medford


Will Mexican Petunias grow under an Oak tree?


The Lady Bird Johnson Wildflower Center, home of Mr. Smarty Plants. recommends only plants native not only to North America (excluding Mexico) but to those areas in which the plants will be grown; in your case St. Johns County on the northeastern Florida coast.  Ruellia brittonia (Mexican petunia) is native to, well, Mexico. Since you live in Florida you should read the following two articles:

Floridata Ruellia brittoniana, see the Warning at the bottom of the article.

Florida Invasive Plant Education

We just learned that petunias are considered to exhibit allelopathy, as well as oaks. Allelopathy is the release of chemicals by the plant which discourages competition from other plants. Maybe the oak and petunia would duke it out, but we are rooting for the tree.

Please note that it is difficult to impossible to grow anything under any tree, including grass, because of the needs of the tree roots for moisture and nutrients from the soil and because of the shade from the tree. Here in Texas, we would vote for the trees and spread mulch under the shade of the tree. See our How-To Article Under Cover with Mulch.


More Non-Natives Questions

Non-native Alocasia in Fayetteville, AR
January 11, 2010 - I am trying to find out information on a plant that I received as a gift called an Alocaiso Plant, It a green, large, shiny green leaf plant with cream colored veins. Very beautiful and I would think...
view the full question and answer

Privacy Tree for Austin, TX
February 10, 2013 - Can you recommend a tall privacy plant similar to the Thuya Green Giant that is suitable to the Austin environment?
view the full question and answer

Best time to plant non-native Crape Myrtle in Fulshear TX
July 01, 2010 - When are the best times to plant Crape Myrtles? My husband and I have just moved to Fulshear, TX (just slightly west of Houston) and being summer, I didn't think this was the best planting period. ...
view the full question and answer

Dying non-native cleyera in Lafayette, LA
August 01, 2009 - Thanks for all the information. One of my six year old cleyera shrubs turned completly brown within two weeks, it is dead. Another is beginning to do the same......do you think it was the recent dro...
view the full question and answer

Identity of mint impersonator in California
May 20, 2012 - Is there such a thing as a mint "impersonator"? There are random 'sprigs' of purple-stemmed, bright green leaf plants in my front yard. We just moved in to the house and I don't want to assume ...
view the full question and answer

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