What are some native wildflowers to plant over a septic leach field?


I would like to plant a native wildflower meadow over my mounded septic leach field as well as in the areas surrounding it. I would also like to plant milkweed to support monarchs. I’m trying to find information about if this is safe with the septic or what types of plants I should use. I understand everything should be shallow rooted. A neighbor told me by law it should only be grass? Is there any information you can point me to?


Rebecca Long, Sustainable Agriculture and Horticulture Professional

There are definitely more pollinator friendly options for your leach field than just grass but because your septic leach field is engineered to serve a specific purpose, you’ll want to keep a few things in mind:

  • Do not add additional soil and avoid rototilling.
  • Plant species that are drought tolerant and do not need irrigation
  • Stick to shallow rooted species and avoid woody perennials whose roots can clog the system
  • No crops or herbs for human consumption
  • Avoid using mulch or allowing the buildup of a large amount of organic matter that could prevent evaporation (an important function of the leach field)
  • Wear gloves when working in the leach field area

More information in our bulletin: Vegetable Gardens and Septic Fields Don’t Match.

A mix of native grasses, groundcovers and small perennial flowers is ideal. This article on planting and maintaining a “bee lawn” is good for inspiration but keep in mind it’s for Minnesota so not all species may be regionally appropriate. Wild Seed Project’s Comprehensive Plant List includes a number of ground covers. This UNH article also includes a list of plants, many of which would be appropriate for Maine as well. While I’m not aware of any laws related to leach field plantings, contacting your local Code Enforcement Officer is always the best bet. Happy planting!