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
2 ratings

Sunday - January 25, 2009

From: Bulverde, TX
Region: Southwest
Topic: Septic Systems
Title: Plants that will not clog lateral lines with roots
Answered by: Nan Hampton and Barbara Medford

QUESTION:

We recently had to replace the lateral lines for our septic tank because wisteria roots had clogged the drainpipes. The machinery tore up our front and side yard,and we are trying to get them back into shape. We'd like to use native plants, or at least plants with low water requirements. Another requirement is that the new plants won't attack our new lateral lines, but none of the books or websites we have studied has information on the compatibility of specific plants and a septic system. Are there any plants we should definitely stay away from? The septic tank man said not to plant photina but he wasn't very helpful beyond that. Can you help? Thanks.

ANSWER:

Well, I have some bad news for you—plants require water, lateral lines have water, so plant roots are going to grow towards the water.  The roots of woody plants will seek a way to get as much water as possible and will make their way into the lateral lines and clog them.  The further away the plants are from the lateral lines, the longer it will take them to get there and begin growing in—but they will eventually get there.  A brochure from the Metropolitan Sewer District of Cincinnati recommends rodding (inserting a flexible cable with a cutting tool on the end into the line) once a year to clear the lines of any roots that have grown into it. 

Your septic tank man was exactly right when he told you not to plant any photinia, but it doesn't have anything to do with whether or not it would plug up the lateral lines. Photinia is a non-native shrub that has been vastly overused and now is falling victim to a fungal disease that is simply wiping some species out. You don't want any woody plants close to your lateral lines, as in trees and shrubs. They are the ones that send roots out far beyond their driplines, sneaking up on you. But you don't want to leave that area completely bare, because you know it wouldn't stay bare, it would get weedy and unless it was mowed, some of those "weeds" would grow up to be woody plants. You are located in Comal County, which means you are sharing in the drought conditions that Central Texas has been experiencing, making any kind of a water source even more attractive to plant roots.

We finally located a website that made specific recommendations on what should be planted above lateral lines-grass! The Ford County Kansas Septic System Information site gives a lot of good information on how to manage a septic system, but the piece of information we were most interested in was that perennial short grasses should be planted above the lines. Apparently, the shorter the grass, the shallower the roots. Furthermore, the grasses will assist in evaporation from those lines, and should thrive with that unaccustomed dose of moisture. We found three grasses native to Central Texas that are less than 1 ft. tall, ordinarily, spread by stolons, and are attractive year-round. Although buffalograss is often planted by plugs or sodding, these grasses can all be seeded. The Native American Seed online catalog features a good selection of grasses, including mixes, and do mail order. Here are three possibilities for grasses for your situation.

Hilaria belangeri var. belangeri (curly-mesquite) - tufted perennial, grows 6" to l' tall.

Bouteloua gracilis (blue grama) - 12 to 14" tall in flower, perennial, turns tan when dormant

Bouteloua dactyloides (buffalograss) - perennial warm-season grass, 3 to 12" tall.


Hilaria belangeri var. belangeri

Bouteloua gracilis

Bouteloua dactyloides

 

 

 

More Septic Systems Questions

Bald cypress knees in leachfield from Ventura CA
March 20, 2013 - Hey, I planted a seedling 20+ years ago which has turned out to be a 40'bald cypress that's now 40'. I'm a native southerner and would hate to cut it down but it's putting up knees in my septic s...
view the full question and answer

Wildflower field for sewage leach field from Olga Washington
August 01, 2012 - I am interested in planting a large native wildflower field at a resort in the San Juan Islands in Washington State. It would be over a sewage leach field for many cabins and bathrooms. Are there any ...
view the full question and answer

Length of root systems for wildflowers over septic system
March 29, 2009 - Mr. Smarty Pants: I want to know the length of root systems for native Kansas wildflowers that will be planted on a Wisconsin mound septic system, which is a special septic system partially above grou...
view the full question and answer

Plants for a Septic Field in NC
August 14, 2013 - What kinds of low water plants can I plant over a new septic field in North Carolina? The area is part sun so I am concerned about having trouble getting grass started.
view the full question and answer

Dog wallowing in damp area in garden from Great Bend KS
March 20, 2013 - I Have a wet area in my back yard that is close to my house. and off my patio there is a water hydrant,gas meter, electrical for my hot tub, my sprinkler valves and pump all there. My dog digs throug...
view the full question and answer

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