Having a septic system in your yard does not have to be an eyesore. Plants such as turf grasses, perennials, wildflowers, and native grasses are suitable cover for septic systems in Minnesota.
The State of Minnesota mandates that a vegetative cover must be established as soon as the topsoil has been placed over the drainfield. Cover establishment can be done by a Subsurface Sewage Treatment System Professional, a homeowner, or a landscaping company; the agreement should be in writing so all parties understand who is responsible for each aspect of the project.
A vegetative cover keeps the soil in place, helps the septic system function by removing moisture and nutrients from the soil, provides an insulating layer for winter protection, and makes the area more attractive. Turf grasses have fibrous root systems that hold soil in place, require maintenance similar to a lawn, and are available in numerous varieties including shade-tolerant to suit site conditions. Perennials, wild flowers and native grasses are an attractive alternative to turf grass, while providing many of the same benefits including fibrous roots, low maintenance (once established), and tolerance of dry soil conditions. Know your site conditions; such as amount of daily sunlight, your USDA Plant Hardiness Zone and percent slope of the system before choosing plants to help ensure plant longevity and vigor.
Planting the wrong cover can damage the area. Avoid annuals as they need to be planted yearly, increasing the traffic over the system. Do not plant edible plants on or near the system (a system failure will contaminate the surrounding area). Trees, shrubs, or plants that have woody root systems should not be placed on or near the system. These roots can interfere with and possibly destroy your septic system. Your septic system should not be irrigated, therefore using plants that thrive on natural rainfall is ideal. The topsoil should not be tilled before planting. Keep traffic over the drainfield to a minimum when planting and weeding.
While the plants are establishing (1-3 years), use mulch or an erosion control blanket to reduce soil runoff. If you are considering an erosion control blanket, know that once it is staked in place covering the entire surface of the drainfield, holes can be cut through the layers to create spots for the plants. The blanket is biodegradable, so it can be left in place. Geotextile fabric should not be used as it may prohibit the exchange of oxygen, which both the system and the plants need.
Since the septic system will need to be serviced about every three years, access covers need to be easily reached. Do not block them. A pot filled with flowers or other impermanent yard decorations may be placed over the covers. Annually inspect your system for animal damage such as burrowing and tunneling before damage becomes extensive.