Guidelines for Planting Over Septic Systems and Septic Fields:
Guide to Planting of Trees, Shrubs, Gardens, Grasses, Ground covers over the Septic Tank, Drainfield or Leachfield. This article explains the types of plants that should or should not be planted over or near septic fields or other septic system components.
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This is a guide for homeowners who are planting trees, shrubs, gardens, ground cover, or other plants near a septic system and who need to know that can be planted near or over septic system components like the septic tank, distribution box, and drain field or soil absorption system.
Planting the wrong things or in the wrong places can lead to the need for expensive septic system repairs.
Planting trees, shrubs, and even some ground covers over septic system components are causes of septic system failure in the drain field, leach field, seepage bed, or similar components.
Planting fruit trees, or vegetables (or anything else edible) over the septic drainfield might produce food that is unsafe to eat:
See SEWAGE CONTAMINANTS in FRUIT / VEGETABLES for details.
An explanation of greener or more brown grass over a septic tank or drainfield is
at SEPTIC TANK GRASS or SNOWMELT.
Many people have written to ask what can be planted over a septic field. Grasses, weeds, flower are OK: The best answer is grass or native grasses and weeds.
Flowers are ok so long as they are not varieties which send down deep roots. In the photograph above these relatively shallow-rooted flowers were set around a septic tank cleanout cover.
They won't cause any damage to the system. But when planning your planting arrangement for flowers over a septic tank, remember that if you plant valuable flowers too close to the access cover to a septic tank or distribution box, those plants may be damaged or destroyed when you have to excavate to open the tank or D-box cover.
Basically, any shallow-rooting planting will be fine to plant over the surface of or near septic tanks, distribution boxes, or septic drainfields.
The photograph abve shows typical grass and a few native wildflowers and dandelions growing in a lawn over a septic system drainfield at a Poughkeepsie New York home.
These plants are not likely to be harmful to the system, they stabilize the soils in the area, and they do not interfere with soil transpiration or evaporation.
Their roots are relatively shallow so these plants are not likely to invade the septic drainfield piping. Grass and native wildflowers are fine over the septic tank or drainfield, and also they are fine over septic mound systems.
The following table of native (to New Zealand) or introduced species of grasses lists species that are considered suitable for planting over an evapo-transpiration system and should be acceptable over a mound system or conventional drainfield as well. Note that other native species local to your area might also be suitable.  We have added Bermuda Grass and Kentucky Bluegrass widely used in the U.S. and some other countries.
Table of Grasses Suitable for Planting Over / Near Evaporation-Transpiration Septic Systems 
|Common Name||Botanical Name||Comments|
Common North American Short-Root Grasses
|Bermuda grass||Typical root depth: 4-6 inches|
|Kentucky Bluegrass species||Typical root depth 6-8"|
|Red fescue|| 27.9 cm / 10.9 in root depth|
Common New Zealand Grasses
|Jointed twig sedge||Baumea Articulata||Carex Comans|
|Longwood tussock||Carex Comans|
|Toetoe||Cortaderia Fulvida||use native species to your area, not invasive pampas grass or other invasive species|
Other Plantings that are Acceptable for Planting Over or Near a Septic Tank or Drainfield / Soakbed
|Flowers, decorative||Shallow-rooted, |
Separately at Trees or Shrubs we provide a similar table of suitable trees or shrubs that can be planted near or in some cases on soakaway beds, drainfields, evapo-transpiration systems. .
Table of Deep Root Grasses Not Recommended Over or Near Septic Fields or Soakbeds
|Native & Ornamental Grasses||Typical Root Depth||Comments|
|Alkali grass||33.0 cm / 13 in|||
|Big Bluestem||96" to nine feet ||Avoid over or near septic system fields & soakbeds or soakpits|
|Eastern bottlebrush||40.5 cm / 15 in.|| May be OK over deep septic fields|
|Indiangrass||73.7 cm / 29.0 in|| Avoid over or near septic system fields & soakbeds or soakpits|
|Little bluestem||64.6 cm / 25.4 in|| Avoid over or near septic system fields & soakbeds or soakpits|
|Switchgrass||70.9 cm / 20.9 in|| Avoid over or near septic system fields & soakbeds or soakpits|
62.5 cm 
 May be OK over deep septic fields
|Sideoats Grama||48" ||
Avoid over or near septic system fields & soakbeds or soakpits
Live in north east florid. What type of grass can I have planted over septic tank drain field?
Grasses are generally OK as long as you're not planting something that sends down deep roots. See the table earlier on this page where we list a variety of grasses whose root systems are generally not very deep. Bermuda grass roots go down 4-6 inches with some variation according to the type of soil. Kentucky Bluegrass roots grow to a depth of 6-8". Either of those should be fine.
Native and ornamental grasses typically send roots down much deeper deeper.
Smooth Brome and Kentucky Bluegrass roots grow to about 10-15" of depth.
Sideoats Grama and Big Bluestem grasses can send roots down to as much as eight feet.
Stay away from these.
Watch out: whatever you are planting on or near a septic system, keep heavy equipment away from the septic tank and soakaway bed or leacfield.
See DRIVING OVER SEPTIC SYSTEMS for details.
Power augers or Roto Rooters™ for plumbing drains can be an effective way to remove a blockage or clog in a drain line.
But if your plumber shows you a tangle of roots when s/he pulls the augur back up the drain line, you should expect that additional repairs will be needed soon.
Even if you pull roots out of the blocked pipe section, the fact that they were in there means a tree, shrub, or other plant has invaded the area and its roots remain outside the just-un-clogged pipe. You can count on the roots re-invading the pipe (and getting at those nutrients) soon. So de-rooting a clogged drain line is a temporary fix.
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(Mar 5, 2014) BJ said:
Why do the flowers planted at the very end of a septic leach field eventually appear to have 'burned up' and what can be done to prevent this? Are there any particular flowers that will work better (perennials for sun)?
Thanks for the question, but sorry, I don't know but I suspect that your drainfield is sending a higher concentration of nitrates and nitrites to its borders - which is common as the leach lines slope down towards their ends. Check the soil nitrate levels to see if they're out of bounds.
Thinking in an opposite direction, also check moisture levels; it would be odd but possible that at your property that area is just too dry for the plantings, OR the opposite could be the case - excessive septic effluent may contain detergents or something harmful to the flowers.
I can't recommend specific plants partly because it's not my expertise and partly because it would be risky to recommend something without inspecting and testing the soil in the area you describe.
(June 23, 2014) Anonymous said:
I want to put in a horseshoe court and it may be over part of my septic leach bed.
My question: I have to drive two steel stakes about a foot down in two places. Will this damage my bed or make it not work?
(June 23, 2014) (mod) said:
Anon you're probably OK, as I'd expect the septic soakaway bed or leachfield pipes to be more than 12" down in the soil. Certainly if you punch a hole in a pipe that's not good - breaking the pipe and inviting a leak.
If you can see the actual location of the trenches by noting the depression lines that often mark their path, be sure to locate your horseshoe court stakes between rather than over the trenches.
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