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

Blocking stolons of St. Augustine grass
July 25, 2008 - I have St. Augustine in my yard, and I am sick of edging the stolons that grow onto the sidewalk and driveway. Is there any way to stop the stolons or block them so that I can just mow and throw away ...
view the full question and answer

Non-native Moth Mullein as a garden plant from Starksville MS
July 09, 2011 - I collected seeds from a beautiful Moth Mullein growing in a lot which will soon be bulldozed. Would I regret sowing them in the back of a sunny perennial bed this fall. These are from the white-pin...
view the full question and answer

Will a non-native smoke tree, Cotinus coggygria, be harmful in Utah
May 08, 2009 - Can one plant a smoke tree in Utah without causing and harm to the environment? I'm worried that this plant may be a species that could cause a problem since I believe it is not a native plant.
view the full question and answer

Non-native bougainvillea in Beaufort SC
July 06, 2011 - Bougainvillea-Can I grow these in Beaufort SC?
view the full question and answer

Oak leaf fall causing ivy damage
August 28, 2007 - I read the A/Q in the Austin American-Statesman Saturday, August 25, regarding the leaves falling now from the live oaks. I am experiencing the same thing, but it is the leaves of my post oaks that a...
view the full question and answer

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