Host an Event Volunteer Join Tickets

Support the plant database you love!

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?

Share

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
1 rating

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

QUESTION:

Will Mexican Petunias grow under an Oak tree?

ANSWER:

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

Best for Austin-non-native loquat or kumquat?
May 04, 2010 - I was wondering which tree is suited better in the Austin,TX, area, the Loquat or the Kumquat, do they lose their leaves in the winter and do they bear fruits?
view the full question and answer

Question about non-native bottle brush bush
September 12, 2008 - I have a bottle brush bush it has not bloomed. I have had it about 6 months planted in the ground. I am worried it may not. can you tell me what you think. thanks lori
view the full question and answer

Thrips on non-native roses in Austin
June 11, 2009 - How can I get rid of thrips that have totally invaded all of my roses?
view the full question and answer

Plants for under non-native fruitless mullberry trees from Ft. Worth TX
June 28, 2012 - I live in Tarrant county, where summer droughts are the norm. I have a 150x50 foot swathe of mature "fruitless mulberry" trees, which create a very shady atmosphere. The soil is clay dominated, ro...
view the full question and answer

Euphorbia 'Cherokee' leaves drying from Benson AZ
October 24, 2012 - I have a Euphorbia 'Cherokee' in a pot and has been growing nicely but some of the leaves are turning red and drying up and falling off. Is this normal for this plant?
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.