Safe plants for septic systems

Many people make the mistake of planting trees and shrubs on or near their septic systems. Improperly locating landscape plants around the septic system can result in one or all of the following:

  • Roots growing into the septic tank
  • Roots growing into the piping
  • Roots growing into the leach field
  • Roots plugging lines
  • The drainage field not being able to breathe

Trees and shrubs should never be planted on or near septic systems because of the ability of the roots to travel. This traveling can and will cause problems. Avoid these problems by choosing the correct plants. Remember, the leach field is the most expensive part of the system, and you will want to protect it from damage.

So what is safe to plant over a septic system or disposal field?

Generally speaking, any shallow-rooting herbaceous plants are OK to plant over or near septic tanks, distribution boxes, or disposal fields. Native grasses, wildflowers, yarrow, chamomile, and clover are plants that can also be used safely. Others include:

  • Fescue
  • Ornamental grasses
  • Bugleweed
  • Carpet heathers
  • Cotoneaster
  • Ground Ivy
  • Kinnickinick
  • Periwinkle
  • Soapwort
  • Bunchberry
  • Chameleon
  • Ferns
  • Mosses
  • Sweet Woodruff
  • Wild Ginger
  • Wintergreen

A few things to keep in mind when planting over septic systems

  • You should not be digging deep holes to plant your plants. Most disposal field piping is between 6″-12″ below the surface. Digging too deep may disrupt the effectiveness of the system which will lead to premature failure.
  • You should always wear gloves when planting in the soil around your septic system. The water from the system, called effluent, can contain bacteria and fungus which can make you very ill. Be extremely careful about getting the soil anywhere near your mouth.

How about vegetables?

As a general rule, no. Some folks may say it is fine to grow vegetables over your septic system, but after reading about how the effluent contains bacteria and viruses, do you really want to? Vegetables that actually root IN the soil are definitely not something you would want to eat anyway. These include carrots, beets, potatoes, etc. Other vegetables that grow on the surface may be contaminated by pathogens that splash up from the soil surface during watering or during rain.

If you absolutely HAVE to plant a tree or shrub near your septic system (within 20 feet), here are a few good and not so good choices:

Not so good:

  • Beeches            Fagus spp.
  • Birches            Betula spp.
  • Elms            Ulmus spp.
  • Poplars            Populus spp.
  • Red Maple        Acer rubrum
  • Silver Maple    Acer saccharinum
  • Willows            Salix spp.
  • Aspen
  • Walnut
  • Blue Mist Spirea

Better choices:

  • Cherries        Prunus spp.
  • Crabapples        Malus spp.
  • Dogwoods        Cornus spp
  • Hemlock        Tsuga spp.
  • Oaks (red, scarlet, white)    Quercus (rubra, coccinea, alba)
  • Pines            Pinus spp.
  • Sourwood        Oxydendrum arboreum

You’ll notice I said better and not best. Although I just supplied a list of better plants, it does not mean that you will never have problems if you plant them near your system, it means they are less likely to cause harm than the previous list.

Do you have a list of safe plants for using over septic systems and leachfields? Be sure to leave a comment and let me know.

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9 Responses to Safe plants for septic systems

  1. Alexandra says:

    I hope you can help me too – i be from germany and never had to do with septic tanks, now i live here in the states and we have one of these things 🙁 i would like to plant lilac and leyland cypress very close to the septic tank, can this cause a problem? thank you so much for your help

    • Dwayne says:

      Hi Alexandra,

      If you have never had a septic tank, they can be confusing. The biggest thing to keep in mind is to get the tank pumped at LEAST every few years. I do mine evry year. If the tank gets too full of solids, they will end up in the leach field; the place where the water dissipates, and plug it up which will lead to it’s failure. Replacing the field costs a lot of money!

      Lilacs and that Cypress can get quite large if left to grow. Regardless, the roots will migrate towards the tank and field to absorb water. The roots may find their way into the tank through small cracks or openings which may cause problems. While working for a local wastewater treatment plant I saw what a mass of fine roots will do to the flow of water in a manhole; block it and back things up!

      Personally, I would keep any trees or shrubs away from the tank (you will need to dig the area to pump it out anyways) and field because of those roots. Not what you want to hear I am sure, but the cost to repair the damage is my main concern.

      • Alexandra says:

        Thank you so much – that is good to know and i will keep this area free 🙂 i don’t want a back up in the house

  2. Tina says:

    I have seen a lot in my 30+ years plumbing Bakersfield. But, for the first time (just the other day) I had a customer call me and ask if it was safe to eat the tomato’s that grew from his septic field. I could only share my personal opinion with the customer but now I’m curious myself..

  3. CapeCodHome says:

    Many of the septic inspections we are called to troubleshoot on have problems from tree roots. In a few cases, the roots have actually crushed the old cast pipes via strangulation.

    Many old systems in this area that do not require an upgrade due to a real estate transfer are plagued by this sort of thing.

    • Dwayne says:

      I agree. Because the roots and pipes are hidden, they often get forgotten. Many folks don’t realize just how much damage those roots can do and when they realize they are having problems it is usually much too late to correct it inexpensively.

  4. Cary says:

    I have the same issue with wanting to plant landscape over the drain field of my septic. One great plant I have planted is the Japanese fiber banana. Very cold hardy, down to 0 with mulch. I am under the impression that the banana root system is shallow and safe. DO NOT TAKE MY WORD FOR THIS, I MAY BE WRONG. If I have made a mistake in planting banana trees over the drain field, Please let me know. Also if any one have info in regards to the septic on the root system of the White bird of paradise plant, I would like to know.

  5. Susan says:

    Very informative post! Thanks! I learned a lot. 🙂
    .-= Susan´s last blog ..Comparing Domestic CarpetCleaning Machines =-.

    • Dwayne says:

      Thanks Susan,

      Most folks don’t realize the potential disaster they are creating when planting trees and shrubs over septic fields. Perennials are ok because of the shallow roots, but deep rooted plants are a no-no.