Plants to Cover Septic Pipes

Grasses

• Grasses are the best choice for septic fields, according to the Washington Sea Grant Program. Many types of ornamental grasses require little maintenance. Blue fescue (Festuca ovina var. glauca) grows from 6 to 10 inches tall and is hardy in U.S. Department of Agriculture Hardiness Zones 4 to 9. This tufted grass grows in dense mounds of blue-green foliage and produces flowers in early summer. It prefers full sun and tolerates dry soil and light shade. Low-maintenance turf grass, such as creeping red, hard and sheep's fescues (F. rubrum, F. longifolia and F. ovina) are also safe for septic planting. Mow once or twice per year. Perennial ryegrass and common Kentucky bluegrass are also safe and can be mowed regularly.

Ground Covers

• Ground cover has spreading, shallow root systems that help prevent erosion and prevent weed growth on the septic field. If your site is shady, plant periwinkle (Vinca major). This shade-loving evergreen grows from 8 to 18 inches tall and spreads into a dense mat of dark, oval foliage. It blooms with blue, funnel-shaped blossoms in spring. Periwinkles prefer rich, well-drained soil and are hardy in USDA Zones 6 to 9. For sunny sites, plant rock soapwort (Saponaria ocymoides). This fast-growing evergreen spreads to 3 feet wide but only 4 to 8 inches in height. It has tiny, dark-green, teardrop-shaped foliage and produces pink to purple flowers in spring. Rock soapwort is hardy in Zones 2 to 7 and prefers well-drained soil.

Wildflowers

• Native wildflowers tend to require less maintenance than introduced species. Appropriate species for septic pipe plantings include rattlesnake master (Eryngium aquaticum), a wildflower that grows naturally near marshes and bogs. Rattlesnake master grows from 1-1/2 to 5 feet tall and has pointed foliage with spiny margins. It blooms in fall with round clusters of white to blue flowers and green bracts. The cobaea beardtongue (Penstemon cobaea) grows to 2 feet in height. This perennial wildflower blooms from spring through early summer with 1- to 2-inch wide, dark purple and white blossoms. Cobaea beardtongues have slightly fuzzy foliage and grow in well-drained soil.

Perennials

• Perennial flowers live and bloom for at least three years. Septic-safe choices include wild ginger (Asarum spp.), a low-growing perennial that reaches heights of 10 inches. Wild ginger blooms in spring with purple to brown flowers and has heart-shaped, lustrous and sometimes variegated foliage. This perennial is hardy in USDA Zones 4 to 8 and prefers shaded sites with moist, rich soil. Violets (Viola spp.) also grow well on septic fields. These perennials are hardy in Zones 4 to 9 and prefer full sun to full shade and moist, well-drained soil. They grow to 8 inches tall and bloom with purple, blue and white blossoms in spring.