Leach Field Gardens
Picture this, an untouched plot of land not too far from the house – full sun, well-drained soil, several thousand square feet in size. The garden designer in all of us starts thinking about the possibilities – a border of native shrubs and small trees, maybe a water feature, perennial beds and a grassy area for kids to play.
BUT…
What if it’s a leach field (a four-bedroom house will require about 4,000 sq. ft)? How do you keep the septic system working properly AND make the best use of the available space?
Planting on the septic drain field, with appropriate plants, can create a beautiful garden, as well as help stabilize the area, reduce the chance of erosion and even make the system more efficient by removing excess moisture and maintaining good air flow.
While turf grass is an option, there are other choices that have the benefit of attractive landscaping, hiding any infrastructure in the area, and providing habitat and flowers for pollinators. Several important considerations are:
· Water requirements – select plants that are drought-tolerant, and won’t need supplemental watering/irrigation once established.
· Root depth – shallow-rooted, herbaceous plants will keep soil in place and require minimal pruning. Avoid plants with long tap roots; they can grow down into the piping. Avoid trees and shrubs for the same reason.
· Maintenance – Avoid plants that need regular fertilizer, pruning and/or dividing. The pipes may be less than 12” from the surface, and can be damaged if plants have to be dug up after planting.
· Avoid foot traffic – Keep turf to a minimum, mow only when necessary.
· Air-flow – Avoid groundcovers that create a thick, dense canopy.
With all of these constraints, what kind of garden is possible? One possibility is a flower-filled, pollinator-friendly design. Ornamental grasses provide structure, while perennials and bulbs add seasonal color. See the list below for examples of appropriate species. Use a slow-growing turf for path, let it grow to at least 4” tall before mowing, and keep foot traffic to a minimum. Avoid raised beds, as the additional soil will prevent the field from functioning properly. Edible plants are not advised, as pathogens and bacteria could be present in the groundwater and hence in the fruit and vegetables.
