En EspaŅol

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
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 - July 10, 2011

From: Nokomis, FL
Region: Southeast
Topic: Erosion Control, Septic Systems, Grasses or Grass-like, Herbs/Forbs
Title: Can Carolina wild petunia be planted over septic tank in Nokomis FL
Answered by: Barbara Medford


Could you tell me the root depth of the Ruellia caroliniensis/ Carolina wild petunia? Trying to determine if I can plant it over septic tank.


From a previous Mr. Smarty Plants answer on plants over a septic field:

"So far as we are able to determine, there is no list or database on root lengths of any plants, including natives. The root length of any plant is variable, depending on the plant size, genetics and age as well as environmental conditions. Keep in mind that when your system was designed, it was a well-known fact that something would grow over it-if not planted by you, then weedy volunteers. If those volunteers are not eliminated, some of them are bound to be woody plants, and that's what you're trying to avoid." 

We see no reason why your Ruellia caroliniensis (Carolina wild petunia) would not be fine in the area of the septic field. The plant roots will help to carry moisture up to the surface, and should not interfere with the lines. This plant is a perennial, and annuals are even better because their roots start over every year, but we don't think the Carolina wild petunia would become a nuisance. Follow the plant link above to find out what light and moisture requirements the plant has, bloom time and color, etc. What you do want to avoid is any woody plant, such as trees and shrubs, over or near a septic line because they will definitely cause problems. Another option is native grasses, not necessarily the kind you mow for a lawn, but taller ornamental grasses. Their fibrous roots will help to hold the soil in plant to prevent erosion and should cause no disruption in the septic lines.


From the Image Gallery

Carolina wild petunia
Ruellia caroliniensis

Carolina wild petunia
Ruellia caroliniensis

Carolina wild petunia
Ruellia caroliniensis

Carolina wild petunia
Ruellia caroliniensis

More Erosion Control Questions

Erosion for check dam in San Antonio
February 13, 2009 - What are the best trees for a shallow soil wind break in San Antonio? I am building a check dam (maybe 2' deep by 20' wide tall) over a shallow limestone gully to slow the erosion. the gully drai...
view the full question and answer

Plants to stop erosion in Arizona
January 17, 2009 - I'm looking for a plant to stop erosion; I have big wash outs that are starting to erode my yard so I guess I'm looking for deep rooting plants. I live south of Tucson, Arizona. If you can advise me...
view the full question and answer

Erosion Control for Salem IN
September 02, 2014 - We've recently had a new pond dug. It is on a hill side and has some very steep and tall banks. We were advised that our best chance of keeping soil from eroding was to plant fescue. I'm not thrille...
view the full question and answer

Low maintenance, shade tolerant groundcover for Pacific Northwest
August 09, 2012 - What's a good low maintenance, shade tolerant ground cover for the Pacific Northwest? It needs to have good erosion control, too.
view the full question and answer

Limiting erosion around pond from Brooklyn Park MN
May 20, 2013 - Minnesota resident, wants to find plant limit erosion from pond?
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.
© 2015 Lady Bird Johnson Wildflower Center