Ask the County Agent: Planting near a septic drain field

By STEPHANIE BUTCHER, UGA-Coweta County Extension Coordinator

QUESTION: How close can I plant to a septic drain field?

AGENT: It depends on what you are planting. Turfgrass is really the best option for septic drain fields, and vegetable gardens should never be planted in drain fields, but as long as you follow a few simple guidelines you can landscape around the septic system area successfully. 

Ornamental landscape plants are broadly grouped into two categories: woody ornamentals and herbaceous ornamentals. Woody plants usually have larger root systems than herbaceous plants and are more likely to interfere with septic systems.

A good rule of thumb for installing woody plants a safe distance from drain fields is to use the ultimate mature height of the selected tree as the minimum planting distance and then increase the distance. For example, if you are planting a crabapple, plant the tree at least 25 feet from the nearest drain line; 50 to 75 feet would be even better. Consider planting smaller and less aggressive cultivars, if possible.

Herbaceous plants, on the other hand, die back to the ground during the winter and include annuals, perennials and turf. Perennials, including turf, will return the next year from their roots, but annuals will have to be re-planted each year. These plants are usually smaller, and their root systems tend to be shallow compared to those of woody plants. They are also generally less aggressive.

Both woody and herbaceous plants can be used when landscaping on septic drain fields as long as a few guidelines are followed. Remember that septic drain field lines are often very shallow, some no more than 6 inches from the surface. Excessive digging, rototilling or other methods of soil preparation for planting can damage these lines.

Don’t choose plants that typically thrive in wet locations. When tree roots invade these septic drain lines, the extra moisture and nutrients favor root and plant growth and lines become clogged and damaged.

Trees to Avoid on Septic drain field Plantings include:

• Willow (Salix spp.)
• Birch (Betula spp.)
• Magnolia (Magnolia spp.)
• Poplar (Populus spp.)
• Elms (Ulmus spp.)
• Some maples (Acer rubrum, Acer saccharinum)

For more information on planting near septic drain fields, contact the Coweta County Extension office at 770-254-2620 or email [email protected] and ask for the publication, Ornamental Planting on Septic drain fields. The University of Georgia College of Agricultural & Environmental Sciences is an equal opportunity, affirmative action organization.

Photo Credit: Clemson University Extension