Explore Plants

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
    
 

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
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

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 Herbs/Forbs Questions

Plants for north side from Dale TX
February 10, 2012 - What native trees and bushes can I plant on the north side of house? Can I use corn meal( I NEED FIGHT A GRASS) in flowerbed and then plant native wildlife seeds(FLOWERS)?
view the full question and answer

Mealy blue sage drooping from Canyon Lake TX
May 07, 2013 - Mealy Blue Sage @ 4 ft Tall - Planted three Mealy Blue Sage last year and they topped out at 2 ft tall. This year they are 4 ft tall in early May, and many of the stems are growing near horizontal...
view the full question and answer

Hyptis alata information for San Marcos TX
April 13, 2012 - We saw a plant called Hyptis olata at the WFC plant sale today and cannot find it in the NPIN list. THis is a new one to us. Can you tell us something about it? THanks.
view the full question and answer

South Austin Groundcovers for Oak Shade
March 29, 2013 - Hi! I live in S. Austin now but used to work at the Wildflower Center! My backyard is shady with several oak mots. Do you have any suggestions as to what if any ground cover will grow in all that sha...
view the full question and answer

Fiber and dye plants at the Wildflower Center from Round Rock TX
May 24, 2012 - When I visited the Wildflower Center recently I noticed a garden labeled as containing fiber and dye plants, but the individual plants and their uses were not all labeled. I would be very interested ...
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.