Extension

When it’s time to plant in the landscape, gardeners typically make decisions of what to plant in specific places based on sun exposure, water availability and soil. Some gardeners, however, will need to think twice about what to plant where if they have a septic system.

 

Many neighborhoods and rural homes are in areas located outside the boundaries of centralized wastewater treatment plants. These homes feature a septic system. Knowing what can and can’t be planted over the lateral lines is essential to keeping the septic system in proper working order.

 

The drain field treats the septic system effluent, and if it isn’t working properly, human health and environmental problems could arise. Anything, including plants, that could interfere with the surface infiltration and subsurface percolation of the effluent in the drain field, as well as the proper functioning of the spray heads at the surface or the subsurface dispersal system, will cause the septic system to fail.

 

Above-ground crops including turfgrasses, native grasses, and annual and perennial plants including wildflowers are the best plants to maintain over lateral lines because of their shallow root systems. Keep in mind that the drain field needs sun to perform optimally so avoid dense groundcovers and lots of tall plants that cast heavy shade. 

 

Gardeners who want to plant root crops such as potatoes and carrots should locate those beds away from the lateral lines. The risk of contamination of the crop is likely if the system would fail and contaminated water came to the surface. Regardless of the type of septic system, edibles should never be planted in the drain field because of the risk of microbial contamination and health risks. This includes all edible flowers, too.

 

Also, avoid planting trees and shrubs near the drain field. Shrubs with an aggressive root system need to be planted at least 15 feet away. Trees need to be planted at least 10 feet farther than the estimated root spread at maturity. For example, a tree expected to be 25-feet tall will likely have a root spread of 25 feet. Therefore, the tree needs to be planted at least 35 feet away from the boundary of the drain field.

 

The septic system, including the lateral lines and the drain field, may take up a lot of space in the yard, but following some of these guidelines will help gardeners have an aesthetically pleasing landscape while protecting the integrity of the septic system.