Native (and other) Plants for Septic Drainfields

 

Many landscapes featuring native plants the one glaring exception to the diversity in seasonal color, floral display and wildlife supported is the septic drainage field. This is often identified in the landscape as a closely trimmed mound of lawn grass. The reasons lawn grasses are used here are the same reasons they do not do much for the environment – shallow roots. And also because that is the general recommendation from nearly ANYONE you ask about planting a septic drainfield.  The comfort of knowing these plants will not grow deep roots that will invade the mechanics of a septic drainfield system outweigh the discomfort of knowing you are not adding anything ecologically to the environment.

We are here to let you know about plants that can do both – they can live on the septic mound without disturbing it and will contribute to your plant community and your habitats with the bonuses of looking good and having seasonal interest.  Maybe it is true – you can have it all. If you are in the early planning stages of your septic or facing the daunting task of having to upgrade or replace, check out this information on Constructed Wetland Septic Systems. 

Septicworks

Illustration: PADEP.gov

New Moon plugs are great for planting in this type of area, the small holes required for plug planting help to ensure you are less likely to disturb the septic mound infrastructure.

According to Virginia Tech Extension shallow rooted plants such as herbaceous perennials are okay to plant in septic drainfields. The term shallow is used relative to those roots of trees and shrubs. Of course we know from the often shared illustration below that one of the reasons native plants are great is because of their deep roots! (note the shallow shallow shallow roots of lawn grass all the way to the left in this illustration – this is why people feel comfortable putting it, and only it, on their septic drainfields.)

 

 

NPGp5_rootsys

Illustration:  USDA NRCS Illinois 

The perforated pipes in a drainfield can be as shallow as 6″ below the surface which explains the concern about planting plants on the site and what the roots will do.  The extensive roots of native plants can actually help clean the water, collect nitrogen and reduce soil erosion on a drainfield without damaging the system itself.

The experts at Clemson recommend avoiding water-loving plants. This is not the place to plant the perennials that are going to send deep roots to suck up as much water as possible. Those roots may end up clogging the perforations of your pipes. This is the time for plants that are happy with the amount of rainfall typical for your area and drought tolerant plants.

Of course, in addition to understanding your growing conditions, you must become familiar with the inner-workings, age, design and limitations of your own system prior to choosing plants.

We have scoured resources and the list below represents plants often recommended for use in planting septic drainfields.  Plants that are most successful and have the greatest potential in this situation are low-maintenance, do not need division, and are drought tolerant. You will find options for sun and shade. Most are native, but we have included some non-native plants as well. Below you will find commonly listed plants recommended from various sources, as well as some of their lesser-known relatives we feel would do equally well and should be planted more. We have also included additional plants we did not see on the lists but fit the criteria of shallow rooted, drought tolerant, low maintenance, that can be considered for a septic drainfield planting.

Grasses & Sedges

Perennials

While this list is long, we feel it is not exhaustive.  For example, most Echinacea and Aster  (and plants formerly known as Aster) will do well in these conditions. What plants have you spec’d in designs or tried in landscapes and had good luck with?


References:

Landscaping Over Septic Drain Fields – Clemson Cooperative Extension

Planting on Your Septic Drain Field– Virginia Cooperative Extension

What Native Plants Can I Plant on My Septic Drain Field? – MSU Extension

Landscaping Over Septic Systems with Native Plants – Purdue Extension

Proper Landscaping On and Around Your Septic System – US EPA

Butterfly Plants for Over Your Drainfield– Ladybird Johnson Wildflower Center

Septic System Management – Landscaping and Other Activities on Your Property  – OSU Extension

Landscaping Your Septic System – Sea Grant Washington

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