Native Plants
![](../_images/smarty_plants.gif)
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.
Did you know you can access the Native Plant Information Network with your web-enabled smartphone?
Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.
![](../_images/mr_smarty_plants_logo_web_200w.jpg)
rate this answer
![](../_images/star_42.gif)
Sunday - March 29, 2009
From: Lawrence, KS
Region: Midwest
Topic: Septic Systems
Title: Length of root systems for wildflowers over septic system
Answered by: Barbara Medford
QUESTION:
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 ground. The topsoil is 12-15" in depth so I need to know the root system length. Some flowers I have in mind are prairie coneflowers, black-eyed susan or variety of sunflower, purple prairie clover, Indian grass. Any grasses you can think of beside fescue, which is boring. This area will never be mowed or only very occasionally. Or if you can direct me to a website or reference book would be helpful.ANSWER:
Sorry, but there is no definitive answer to your question. 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 volunteeers. If those volunteers are not eliminated, some of them are bound to be woody plants, and that's what you're trying to avoid.
All the research we consulted agrees that the best plant material for the earth covering septic systems is grass. They have fibrous roots and will help hold the soil in place, help prevent erosion on your raised system, conduct some of the moisture to the surface of the soil, and are easily maintained. Wildflowers will fall into the same category, particularly the annuals. The one thing you want to avoid is woody plants, especially trees, as they develop long roots that stretch out beyond the canopy of the tree and would go for the moisture in the septic lines. Those roots can certainly clog the lines, so keep the trees away.
We are going to go to Recommended Species for Kansas, select first on herbs (herbaceous flowering plants) in Habit and annual in Duration. We will then do the same thing in grasses, but not indicate a duration. Even perennial grasses are going to maintain a root system that is compatible with the septic system. If your area has a lot of shade, or you are interested in other species, you can do the same thing, putting in the different characteristics (like bloom time and color, for instance) and make your own selections. We included those on your list, all of which are native to Kansas and excellent choices.
Grasses for Kansas
Sorghastrum nutans (Indiangrass)
Andropogon ternarius (splitbeard bluestem)
Aristida purpurea (purple threeawn)
Bouteloua curtipendula (sideoats grama)
Bothriochloa laguroides ssp. torreyana (silver beardgrass)
Carex blanda (eastern woodland sedge)
Calamagrostis canadensis (bluejoint)
Chasmanthium latifolium (Inland sea oats)
Wildflowers for Kansas
Ratibida columnifera (upright prairie coneflower)
Rudbeckia hirta var. pulcherrima (blackeyed Susan)
Dalea purpurea (purple prairie clover)
Amphiachyris dracunculoides (prairie broomweed)
Aphanostephus skirrhobasis (Arkansas dozedaisy)
Chamaecrista fasciculata var. fasciculata (partridge pea)
Coreopsis tinctoria (golden tickseed)
Gaillardia pulchella (firewheel)
More Septic Systems Questions
Native plants to replace St. Augustine over septic area
November 02, 2009 - Hi. We're new to Orlando, FL and need some help with plants that would be suitable to grow over our septic field. It's on the west side of the house, full sun.
We live in a subdivision that r...
view the full question and answer
Tree for on top of sewer lines from San Antonio
March 16, 2013 - I am looking for an evergreen small tree with taproot to plant in a very small front yard near the sidewalk and possibly on top of or nearly on top of sewer lines. Would a Mt. Laurel be the choice? ...
view the full question and answer
Windbreak for Eastern Kansas
July 17, 2011 - I need to plant a fast growing windbreak near my lateral lines for a septic tank. We obviously can't have anything that would interfere with the laterals but I desperately need a North wind break. ...
view the full question and answer
Wildflowers and grasses for a septic field in Maine
November 18, 2010 - Mr. Smarty Pants: I want to know the length of root systems for native Maine wildflowers that will be planted over a septic system drain field in Maine. Also any grasses you can think of. This area ...
view the full question and answer
Native plants for septic field in Austin
March 14, 2011 - Do you have guidance for west Austin residents regarding landscaping a septic field with native plants?
view the full question and answer
Support the Wildflower Center by Donating Online or Becoming a Member today. |