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?

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
Not Yet Rated

Saturday - March 30, 2013

From: Houma, LA
Region: Southeast
Topic: Invasive Plants, Non-Natives, Planting, Herbs/Forbs, Trees
Title: Planting petunias around base of oak tree from Houma LA
Answered by: Barbara Medford

QUESTION:

I live in south Louisiana and I want to plant petunias. Can I plant petunias around the base of an oak tree?

ANSWER:

There are 8 members of the genus Ruellia (wild petunia) native to North America, of which Ruellia caroliniensis (Carolina wild petunia) and Ruellia nudiflora (Violet ruellia) are native to in and near Terrebonne Parish in the southeastern portion of Louisiana. If you follow the plant links to our webpage on each plant you will learn that both like moist soil and can tolerate some shade. That would mean they could grow under an oak tree. BUT, you need to read this previous Mr. Smarty Plants answer about allelopathy in oaks and Ruellia brittoniana, which is the non-native Mexican petunia. Also see this Florida article about Ruellia or Mexican Petunia and note the warnings about its invasiveness.

Now, lets talk about the other petunia. Pelargonium (petunia) is a genus of 35 species of flowering plants of South American origin, closely related to tobacco, cape gooseberries, tomatoes, deadly nightshades, potatoes and chili peppers; in the family Solanaceae. From Google, here are pictures of the "other" petunia.

Frankly, we don't think either the native or non-native petunias would prosper under your oak tree, and the non-native members of the Solanaceae famly apparently need full sun, which we consider to be 6 hours or more of sun a day.

 

From the Image Gallery


Carolina wild petunia
Ruellia caroliniensis

Violet ruellia
Ruellia nudiflora

More Trees Questions

Shade trees for Spring TX
August 17, 2011 - Dear Mr.Pants, our west-facing backyard in Spring, Tx, is unbearable in this Summer's heat. Neither us nor the neighbors has any backyard trees established yet, as the subdivision is pretty new. C...
view the full question and answer

Possible woodpecker damage in Monterrey Oaks
November 17, 2006 - I live in NW Austin and have two Monterey Oak trees, each about 30 - 45 gal in size. They both were planted approximately 9 months ago. Both trees seem to have some cracking bark on the trunk along w...
view the full question and answer

Brown leaves on Burr Oak from Dripping Springs TX
October 05, 2013 - We have recently planted a 15 gal. burr oak in an correct hole with great soil and plenty of watering in. We have noticed some brown leaves. Should we be worried?
view the full question and answer

Need suggestions for trees with non-invasive root system in Paramus, NJ.
August 23, 2011 - What trees can I plant in New Jersey with non invasive root systems? We lost our tree to a storm and are looking for a viable replacement.
view the full question and answer

Smarty Plants on women trying to conceive
July 10, 2005 - RE: Eucalyptus. Is this bad for women trying to conceive? The smell is very powerful.
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | JOBS | SITEMAP | STAFF INTRANET
© 2016 Lady Bird Johnson Wildflower Center