Q&A about planting grasses, trees, shrubs on or near septic tanks and septic fields:

Questions and answers about safe distance from the septic fields for various plants.

This article series 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.

Plant Distance & Plant Type FAQs for Septic Fields

These questions and answers about planting near septic systems were posted originally at PLANTS & TREES OVER SEPTIC SYSTEMS - be sure to review that article.

On 2018-09-08 by (mod) - safe planting distance for hydrangeas near septic system

Thanks for asking, Janet.

Hydrangeas use a rhizome type root that stays principally in the top 6-inches of soil - so it would not be expected to invade the drainfield absorption trenches or drip lines.

It would be smart to keep the plants away from the drainfield by a distance no less than the full width of the plant's visible foliage when it will be mature. As a mature plant is about 6 feet (2 meters) in diameter, a ten foot distance ought to be safe.

On 2018-09-08 by Janet

I am wondering if I can plant hydrangeas near my septic drain field ...what would be a safe distance from the drip lines?

On 2018-07-09 by (mod) - clear overgrown area around and over the septic fields

Makes sense to clear everything but grass. Also looks pretty close to those trees.

On 2018-07-09 by AJ

Here is the sketch of the system.

do you if i can aerate over the septic tank. i have grass growing there but it is thining and i wanted to aerate and add more grass.
Thanks!

On 2018-07-09 by Anonymous

attached is the pic. As you can see it full of all kind of stuff.i was going pull all them out - it's a major eye sore.

my father in law is insisting on pulling all the weeds, putting down loam over it and growing native grass - is that a good idea?

On 2018-07-03 1 by (mod) -

With the apology that I can only answer conceptually because I can't see your weeds nor do I know the construction of your drain field, the worry would be plants who send roots down deep enough to invade the absorption bed trenches and piping.

I suspect that most surface weeds are not a problem and I would just mow them when I cut my grass. If you wanted to be scientific about it or do the sort of experiment that I might try, you could pull out or dig up a couple of the most ugly looking or larger weed plants or other plants over the drainfield and take a look at the depth of their roots.

If you thought that was not deep enough to invade the drainfield trenches you wouldn't worry about them.

On 2018-07-03 by AJ

Thank You for responding promptly. I did not see the article you mentioned. Now i know.

For all kind of weeds growing on the drainfield, should i just pull them out or give up and let them run amok? It looks terrible.

Thank you,
AJ

On 2018-07-02 by (mod) - importance of avoiding covering a drainfield with anything that blocks its exposure to the air.

AJ

Thank you for the question and for this chance to clarify the importance of avoiding covering a drainfield with anything that blocks its exposure to the air.

You didn't read about plastic in the article on THIS PAGE because this is an article about plants. As editor I worry that if I try to put every single mistake about septic drainfield on a single page the article is so long that it's not readable. However this article *series* does include the plastic over drainfield warning.

Throughout this article series we warn against both invasive roots that can damage a septic field by clogging its pipes, and against the use of plastics, pavers, or anything else that blocks both the transpiration/evaporation function of the drainfield beds (disposal of some effluent by evaporation)

and also that would block the movement of oxygen into the soil (absence of oxygen means that the necessary bacterial action on sewage effluent cannot take place, and in turn that means that the drainfield cannot work and that it will send pathogens into the environment including the aquifer - peeing in the water supply so to speak.

Plastic weed barriers would be an example of such a product that should not be used over a drainfield.

Plastic's effect on a soakbed or leach field (or drainfield) is discussed as well at SEPTIC DRAINFIELD FAILURE CAUSES https://inspectapedia.com/septic/Leach_Field_Failure_Causes.php

Excerpt: Don't seal the drainfield or soakaway bed top from contact with air by leaving a plastic liner of any sort - ice rink, swimming pool, tents and tarps in place. Don't seal the drainfield or soakaway bed top from contact with air by leaving a plastic liner of any sort - ice rink, swimming pool, tents and tarps in place.

Any strategy for removing weeds anywhere on a property should consider the effect of use of chemicals or weed killers on the environment. That means that some weeds are removed by removing the offending plants and where you use an herbicide you should research its effects as well as, of course, following the manufacturer's directions.

On 2018-07-02 15:00:51.171507 by AJ how to kill weeds growing on the drain field.

Hi,
I did not see anywhere in article related to spetic tanks on how to kill weeds growing on the drain field. How does one go about doing it?
I was planning to put plastic sheeting over the "baby" weed next year, but this article https://s3.wp.wsu.edu/uploads/sites/2144/2015/03/Spotlight-on-Planting-over-Septic-Drainfields.pdf says not to put any platic sheeting.

What do i do? The whole of the field is full of ferns, blackberry brambles etc. Overwhelmed on tyring to figure out how to kill them off.

Thank You,
AJ

On 2018-06-06 by (mod) -

Feather reed grass ( Calamagrostis x acutiflora ) typical root depth is about 12 inches. If your septic field trench gravel top is 24 inches down you're probably ok.

On 2018-06-05 by Elizabeth

Can feather reed grass be planted over a sceptic field
Calamagrostis x acutiflora also Festival glaucoma Elijah Blue
I wanted to use 2ground covers vinca and creeping Jenny any problems?

On 2018-05-29 by (mod) -

Matt,

No, you're fine. If the home has been converted to a public sewer line, or if the currently-in-use septic absorption field is nowhere near the proposed tree site, and if there is no chance that someone is going to want to return to using this septic area (such as an alternating-bed septic design), then you can go ahead.

On 2018-05-29 by Matt

I have a septic system/drain field that is no longer in use for quite a few years. Am I still restricted on what I can plant on top of it? I would like to put a flowering ornamental fruit tree in the area of where it is but am not sure if it is okay.

On 2018-05-13 by (mod) -

Terri

From what I have read a rose of sharon plant can fall prey to any of a number of plants diseases, insect pests, and more rarely overspray from certain chemicals biocides that might be used around home.

It doesn't seem likely that would be the relationship to the septic system that would be at fault unless the tree is in fact drawing water from sewage effluent that was overdosed in some type of antifreeze.

If your research finds that that is the case you need to be concerned that the septic system itself has been damaged by such chemicals.

On 2018-05-13 by (mod) -

Kim

Dogwood trees are shallow root plants that rely mostly on surface water. So if you keep the tree a minimum of one preferably to Ultimate Branch diameters away from the drain field and septic tank you're probably fine. I would estimate that as 15 or 20 feet minimum distance. 30 would be better.

On 2018-05-13 by Terri

Its over a drain field

On 2018-05-13 by Terri

I have a rose of sharon in the back yard.looks good the last few years. This year nothing ,its all dead Also have hydrangeas did good for 2 years now dead this year.

On 2017-10-31 by Kim

I want to plant a tree for some shade but I have a septic tank in my front yard. I have heard of dogwood trees but I live in zone 10 So I'm not sure what to do or what to plant or how far?please help

On 2017-10-13 by (mod) -

Stan,

My quick check shows that heather has a shallow root system - enabling it to grow over rocky surfaces. But depending on where you live the heather may not flourish if it's too dry;

So the answer is that most plant experts say "no problem - shallow roots", but I worry that with many normally shallow-root plants the plant might amend its behaviour and send roots deeper than normal, attracted by the unusual nutrients below, particularly if it's not getting enough water.

On 2017-10-13 by Stan G

Can you grow heather and heath over a raised septic system

On 2017-08-03 by Brad

My septic bed is covered in vine ground cover ( grape I believe) would it be better to be removed .

On 2017-06-20 by DorisH

Can I plant spirea over my septic tank (not my djainfield)?

On 2017-04-12 by (mod) -

Terry, Horsetail reed (Equisetum or family Equisetaceae of which there are about 20 species) uses a deep root system, extending several feet into the soil or deeper and extending horizontally as well.

Also known as "Scouring rush" the plant is described by horticulturists as one that's therefore difficult to control or remove - just as you suggest.

I'd be afraid to plant it closer than 50 feet to a septic drainfield.

On 2017-04-12 by Terry Lefor

Hello, wondering about horsetail reed for perimeter fencing around my yard. the yard contains the septic bed. Does this grass have a far reaching root system? I understand it is fairly invasive and can take over the garden if not pruned properly.

On 2017-03-24 by (mod) -

Anna

Thanks for the suggestion. "Native" flowers will be native or not depending on where you live. But most flowers do not have long-deep root systems that would make me worry about root damage to the septic soakbeds.

Planting flowers over a soakbed or septic field for pure enjoyment is fine - I'll research and list any deep-rooting exceptions here.

However I would be concerned if you plan to cut and harvest and give-away or sell septic field-grown flowers if the flowers are planted in an area where they may be wet by an aerobic septic effluent spray system or by pathogen-contaminated soils in an area where a septic soakaway bed has failed, sending sewage effluent to the surface.

Native or Wildflowers to Keep Off of Septic Areas

Since the list of wildflowers is huge, and since it varies by where you live I"ve suggested that most wildflowers are fine to plant over or near septics within the constraints I suggested above.

So I'll just list exceptions: flowers to keep off of the septic area. Some plants are considered weeds in some areas and valuable plants or flowers in other areas - again it depends on where you live. Readers are welcome to comment to add suggestions.

Bindweed (creeping jenny) - considered a pest, is a deep-rooted plant.

Canada thistle is a deep-rooted perennial to keep away from septics.

Dandelion should really not be on septic systems though I know they're ubiquitous. Some Dandelions can produce an incredible taproot that is usually just about a half/meter in depth but it's roots can go to 10-15 feet (4.5 meters) - which explains why they're so hard to pull out.

Probably OK but at the edge:

Sagittaria latifolia produces an edible root that can be about 1/2 meter deep - just enough to begin to get attracted by the top of some soakbed trenches depending on trench depth.

On 2017-03-24 by Anna

How about a list of native flowers which are ok to be planted over the septic field? It would be so helpful!

On 2017-01-01 by (mod) -

Deer over the septic tank - let's hope it has a sound solid concrete cover, not a rusting steel one, or you may find a deer IN the septic tank.

On 2017-01-01 by Edna

what about purslane over the septic tank; since it grows as a weed, it would be no loss if we had to dig it up. And deer like to browse it, so I hope they enjoy it and we get to see them near our home in the woods!! Any advice?

On 2016-05-02 by (mod) -

Anja,

I can only GUESS that someone is worried that there is an old, unsafe septic tank, perhaps one with a home-made or rusted steel lid. If someone falls into a septic tank, most often they die. Quickly.

I would not lease such a property before finding out just what is installed, and making sure that the property is safe. In my opinion both property owner and leasee (you) could face liability if someone is injured. It's one thing for an owner to tell you not to walk on the grass, and it's a different problem controlling where visitors to the property may walk. Meanwhile, if the question is one of safety, rope off the area and keep people away.

If the owner thinks that stepping on a (safe, secure, properly-installed) septic tank or walking over one is going to hurt the function of the septic system, she's mistaken.

If the owner thinks that the reason to keep off the grass is because the septic system is in failure - pushing sewage effluent to the ground surface, an unsanitary condition - then she's right: you do not want people visiting your cafe to be walking in sewage effluent.

If that's the problem I would not lease the property until the septic drainfield has been repaired or replaced.

On 2016-05-02 by Anja

Hi there!
I'm about to lease a Cafe with nice grounds around the main building, but I've been told no-one is to step on the grass because we have a septic tank... why is that? Do you know? Thank you!

On 2016-04-02 by (mod) -

BonBon - I apologize: we've written so many articles on this (well I have) that it can be tough to find exactly what you need when landing on an InspectApedia page from the search engines.

IN the live article links a little further up on this page, you want to see TREES or SHRUBS OVER THE SEPTIC FIELD or TANK

The safe distance from septic fields for trees depends on the tree species.

Check the root depth for the fern species you want to plant.

Compare that to the distance from the soil top to the top of the actual gravel-trench that contains the nearest individual leach line in the mound system.

If you've got a foot or more between the root bottom and the trench top you're pretty safe for ferns.

On 2016-04-02 by BonBon

We need a mound system installed. They want to put it near a large group of trees on top of a hill. Is it a problem if I plant ferns over the mound? How far away should trees be from a mound?

Question: flowers at the septic field borders burn up

(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)?

Reply:

BJ

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.

Question: playing horseshoes over the septic leaching bed or soakbed

(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?

Reply:

(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.

On 2013-03-20 by (mod) -

Anon,

I don't think so, not at all; usually the reason we see those steep sides was one of cost at time of construction. The operational portion of the mound is the soil beneath the effluent distribution pipes; In fact you should not ever see effluent flowing out of the sides of the mound. If you do, just adding soil is not really a good repair.

On 2013-03-20 by Anonymous

are there any issues with using soil to transition the sides of the sandmound into the existing yard as to not have such a steep transition from the top of the mound to the existing ground?

In other words, are there any issues with using top soil to go from the top of the mound to the existing yard, but not covering the top of the mound, so there's no steep slope on either side of the mound?

On 2013-03-19 by (mod) -

I think that might be OK so long as

- the total thickness of added soil is not burying the mound so as to impact transpiration and evaporation;

- the process doesn't involve driving over and thus damaging or compressing the mound or mound soils;

So keep the 1/4-ton boulders somewhere else.

On 2013-03-19 by Connie

We have a newly installed sewer mound in an well manicured yard. Can we cover the mound with landscape fabric and put dirt, gravel, rocks and drought tolerant rock garden plants on the mound?

On 2012-08-13 by (mod) -

Anon

If the trees are off of the mound itself you ought to be able to work safely to cut the tree down to the ground and keep it mowed (the minimum action) or presuming you can drive a tractor to near the trees without driving across the septic fields at all, pull 'em out slowly, watching to be sure you're not disrupting the mound.

If the mound is being disrupted the roots have already invaded and a bit of root cutting would be helpful.

On 2012-08-12 by Anonymous

I have a few alder trees at the back side of my septic mound. How do I get them out before they cause damage? They are about 2" diameter and at the bottom edge in about 3 feet.

On 2012-07-30 by Doreen

Thank you. I will research the issue using the information that was provided.

On 2012-07-27 by (mod) -

Root span of hydrangeas:

Doreen, the root expansion range of hydrangeas varies by species, but some are enormous. For example climbing hydrangea plant roots can extend more than 80 feet.

See Yeh & Chang "Growth and flower initiation in hydrangea as affected by root restriction and defoliation" or perhaps in a different approach, using buried pots to control the root growth of hydrangeas, check with the Horticultural Research Institute (HRI) for a copy of Reed et als, "Verification and Establishment of Hydrangea macrophylla x H. paniculata Brussels Lace Interspecific
Hybrids"

On 2012-07-27 by (mod) -

MDE:

We agree that bamboo not only has a long horizontal root system, that plant family procreates by horizontal root expansion - so it will just keep on expanding outwards from its original point unless control measures are taken.

On 2012-07-26 by Doreen

Can you plant hydrangeas near a septic system aproximately 5-7 feet from the perimeter of the system/field.

On 2012-06-05 by (mod) -

MDExperimenter

In my experience bamboo has a long horizontal root spread system.

On 2012-06-05 by (mod) -

Jennie,

Yes.

On 2012-06-05 by (mod) -

Tracy V: regarding dog feces and girardia and blueberries, there is a greater risk of irrigation or spraying fruits & vegetables with unsanitary water than of the passage of Giardia through the plants' root system.

But to be better informed we suggest you ask your library (or web search for) for a copy of Larry R. Beuchat's "Ecological factors influencing survival and growth of human pathogens on raw fruits and vegetables" published in Microbes and Infection, Volume 4, Issue 4, April 2002, Pages 413 - 423

- this is a nice example but not the only article that explains the level of hazards. The citation is in our references at the end of this article along with another that you might find interesting, Anthony, Jean-Paul (2008) (regarding the properties of blueberries).

I am very doubtful about the success of trying to sanitize the soil around your blueberry plants, both because of the risk of ineffectivenss, or lack of necessity (assuming you removed the feces), and because of the risk that you simply kill the plants.

On 2012-06-05 by Jennie, Michigan

I want to plant a dappled willow at the edge of our house but the septic field is approximately 10-15 feet away. Is this too close?

On 2012-02-27 by Tracy V

We recently adopted a dog and, without thinking, let him defecate near our blueberry bushes for a couple of days--once we realized this could be a problem, we stopped allowing this, but not before we discovered that the dog had the parasite giardia and therefore certainly contaminated the soil.

We are now wondering what to do to treat the soil to 1.) keep the dog from getting reinfected, and 2.) make sure our blueberries are edible five months from now. Do we need to avoid eating the fruit? Please help!

Thanks, Tracy

On 2012-01-03 by MDExperimenter

Would large-diameter timber bamboos planted in the leach field cause eventual problems? We are trying to cultivate some, and were hoping that if planted there the effluent might provide a nutrient source directly or indirectly.

On 2011-08-17 by (mod) -

Deborah, please try PLANTS & TREES OVER SEPTIC SYSTEMS link in our ARTICLE INDEX to read the article titled "Gardens Near Septics" for details.

On 2011-08-17 by Deborah Turel

What is a safe distance for a vegetable garden to be from a drain field ? My garden is about 30 feet down slope from a drain field, I have planted some woody flowering shrubs 20 feet below drain field, then 10 more feet to garden. All is healthy but leafy, like perhaps too muchnitrogen.

On 2011-08-08 by (mod) -

Roughly a foot long roots should be fine; typically the top of a drainfield trench is more than 12" down.

On 2011-08-07 by Anne Taylor

How long are the roots on "shallow-rooted" flowers referred to above? For example, should six inches be okay? How about eight inches?
Thanks.

On 2011-08-05 by (mod) -

The impact of a drainfield on crops depends on the depth of effluent in the soils, the root structures and other crop natures - some plants may be more resistant to pulling up bacteria and other contaminants. The issue of deep rooting crops invading the drainfield probably doesn't occur - I doubt you have crops whose roots extend to that depth.

In sum, I'd not bet my business on selling crops grown over a septic drainfield and I'd not be happy with a drainfield that does not treat effluent.

On 2011-08-05 by (mod) -

Dakota
Unfortunately driving farm equipment over a drainfield will almost certainly ruin it if the field is close to the surface; and when a drainfield is so deep as to avoid frost (you'd need to be down 8 feet or so in your area) your field may be protected from surface equipment but it will no longer be treating the effluent - as there is inadequate aerobic bacteria at that depth - so you may be disposing of effluent but you're not treating it - you're peeing into the local aquifer and wells.

On 2011-08-05 0 by Dakota Farmers Wife

We are considering installing a small RV park on one end of our 80 acres to house oil field workers. We are wondering if it would be ok to put our septic system drainfield, under an area that we farm. We grow wheat, flax, and sometimes peas. Since ND gets so cold we have to put our drainfields in very deep Does anyone know if crops would bother the drainfield, or if the drainfield would make the crops toxic?

On 2011-05-04 by (mod) -

Argentine Bahia Sod is used especially in Florida where it likes wet soils. We haven't found a good citation on the aggressiveness of the root system for Argentine Bahia grasses. By aggressiveness I mean that some root systems are pushier than others at invading or even dislocating buried pipes and structural foundations (and sidewalks.

But certainly a root system that is 7-10 feet deep, while drought resistant, includes a real risk that the roots will invade a typical septic drainfield system over which it is planted. That would be enough to discourage me from its use over a drainfield. Adjacent to a septic drainfield, 15 feet away, should be no worry.

On 2011-05-03 by sue

Is it safe to plant Argentine Bahia Sod over a septic drain field? I understand that the roots of this grass can grow as long as 7 -10 feet.

On 2011-04-30 by (mod) -

Distance from septic TANK to plantings:

A vegetable garden 20 feet from a septic tank should not damage the tank and PROVIDED that the septic tank and its piping are not leaking, and that the distance to the drainfield is greater, you may be fine. IF the septic tank is leaking effluent into soils close by, vegetables, especially root vegetables may be unsanitary.

In the ARTICLE INDEX take a look at the links titled:
Gardens near Septics
and
Trees and Shrubs

for details about these distance recommendations to avoid root damage to the drainfield and to avoid unsanitary vegetables or fruits.

On 2011-04-30 by yvettedmasb@hotmail.com

I have a vegetable garden about 15-20 feet from the tanks near the house; there is no mention of distance. How far do forsythia roots grow?

some trees have grown wild in the drainfield-sounds like they should be removed...Maple and tulip?

...

Continue reading  at PLANTS & TREES OVER SEPTIC SYSTEMS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• PLANTS & TREES OVER SEPTIC SYSTEMS
  • GARDENS NEAR SEPTICS
  • GRAZING ANIMALS OVER SEPTIC SYSTEMS
  • GROUND COVER, IVY OVER SEPTIC FIELDS
  • ROOT KILLERS in SEWER LINES or SEPTIC PIPES
  • SEPTIC TANK GRASS or SNOWMELT
  • SEPTIC TROUBLE SIGNS, OTHER
  • SOAKBED SOIL CONDITIONS
  • SEWAGE CONTAMINANTS in FRUIT / VEGETABLES
  • TREES or SHRUBS OVER THE SEPTIC FIELD or TANK
• SEPTIC TANK & SYSTEM CARE BASICS

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PLANTS & TREES NEAR SEPTIC SYSTEM FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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INDEX to RELATED ARTICLES: ARTICLE INDEX to SEPTIC SYSTEMS

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