How to Plant a Garden in Relation to a Septic System Drain Field

Identify where your drain field is located. If you do not have the septic plan, a copy of it may be on file with the local health authorities. It is important to know the precise location to avoid damaging the lines with digging or overwatering.

Conduct soil tests periodically to monitor the pH of the soil, salt level and other nutrients. Abnormal levels may affect the plant choices or require corrective procedures. Add lime if the soil is too acidic for the plants you want to grow. You may need less fertilizer since some of the salts in the effluent may provide nitrogen, phosphorus and potassium needed by your plants.

Avoid tilling or digging the soil more than a few inches when preparing the site. Lightly work in amendments to the first couple of inches of soil, and allow them to leach through over time rather than digging them in.

Select ornamental herbaceous perennials, annuals and ground covers with shallow roots that do not have high water requirements. Some good choices include bee balm, milkweed, hollyhocks, salvia, marigold, zinnias, geraniums and petunias.

Avoid trees and shrubs if possible. If you must include them, place them at the far end of the drain lines where there is less moisture in the soil and less chance of disrupting drain lines. Select small species that have fibrous roots as opposed to a taproot; examples include boxwood, holly, dogwoods and crabapples. Seek clarification from experts if there's any doubt about plant suitability.

Water judiciously. Keep in mind that the purpose of the drain field is to promote evaporation. Excessive irrigation does not promote septic efficiency.