What are the best native ornamental grasses to plant on a septic drainage field in zone 5a/4b?


What are the best native ornamental grasses to plant on a septic drainage field in zone 5a/4b?


Jonathan Foster, Home Horticulture Outreach Professional

As you may know, leach fields are specially engineered structures and care must be taken with anything planted on top of them, as deep root systems can clog, damage, or otherwise interfere with the porous layers. Most common Maine ornamental grasses like big bluestem and switchgrass have the capacity to develop surprisingly deep root systems over time, and so I typically recommend using turfgrass instead when planting over the leach field. If the area gets a lot of foot traffic and is sunny, I would recommend a Kentucky bluegrass mix, but if the field is a bit out of the way and/or shady, you could consider using a fine fescue-dominant mix (which is a bit more drought tolerant, appropriate for the generally well-drained nature of this planting site). If you choose to pursue this approach, please check out our UMaine Cooperative Extension Bulletin #2367, Establishing a Home Lawn in MaineUMaine Cooperative Extension Bulletin #2243, Maintaining a Home Lawn in Maine, and UMaine Cooperative Extension Bulletin #2166, Steps to a Low-Input, Healthy Lawn.

That said, if you are more concerned with the “ornamental” side of things than the “grass” side of things when it comes to your leach field, there are some other options for groundcover. This great leach field resource from the UNH Cooperative Extension gives a list of potential perennials with appropriate root systems that you could consider planting to enhance the field’s aesthetic appeal over simple turfgrass. As mentioned on that page, it’s a good idea to get the soil tested before planting anything to check the site’s pH (which can vary quite a bit in soil over leach fields)–you can find instructions on how to do so at the UMaine Soil Analytical Lab’s website.