Landscaping Your Septic System

Is your septic system drainfield an eyesore? Are you unsure how to garden and care for it?

Here is a guide to the do's and don'ts of landscaping your drainfield.

• Questions and Answers
• Plants You Can Grow On Standard Drainfields
• Resources and Additional Information

Landscaping Your Drainfield: Questions and Answers

Your drainfield represents a substantial investment. Treating it right, and protecting it from damage, can save considerable time, work and money.

1. What can I plant over my drainfield?

Grass is the ideal cover for drainfields. Grasses can be ornamental, mowed in a traditional lawn, or in an unmowed meadow. Or, you can try groundcovers and ferns (see questions 11 and 12 for more details.) The key to planting over the drainfield is to select shallow rooted, low-maintenance, low-water-use plants. For those whose tank-covers are buried, keep in mind that plantings over the tank - from inlet to outlet - will have to be removed every 3 to 4 years for inspection and pumping.

2. How close can trees and shrubs be to the drainfield?

Trees or large shrubs should be kept at least 30 feet away from your drainfield. If you do plan to plant trees near a drainfield, consult an expert to discuss your ideas and needs. Trees and shrubs generally have extensive root systems that seek out and grow into wet areas, such as drainfields.

3. Can I plant a vegetable garden over my drainfleld?

No. Growing vegetables over a drainfield is not recommended. Vegetables need watering, and excess water in the soil reduces its ability to treat wastewater. The deep roots of some vegetables may damage drainfield pipes. Bed preparation, such as rototilling or deep digging, can also damage pipes.

4. What about landscape plastic or fabric under mulch?

No. Plastic reduces the necessary air exchange in the drainfield soil. Even mulch or bark over the drainfield is not recommended, because it reduces air exchange and retains water.

5. Can I build a carport or camper pad over the drainfleld? How about a tennis court or a nice hot tub?

No, for two reasons. First, you should avoid driving over the drainfield; the pressure of vehicles and heavy equipment compact the soil and can damage pipes. Second, impermeable materials such as concrete and asphalt reduce evaporation and the supply of oxygen to the soil. Oxygen is critical to the proper breakdown of sewage by soil microorganisms.

6. How about putting my carport over the replacement area?

No. The designated drainfield replacement area (reserve area) should be left undeveloped and protected from compaction.

7. Can cattle graze over the drainfield? Just one horse?

Livestock should be kept off of drainfields. In the winter, livestock trample and muddy the soil; in the summer they compact it. Again, this is not good for the soil's ability to exchange oxygen. So, sorry, even one horse is not recommended.

8. Rain water is directed onto my drainfield. Is this a problem?

Yes. Downspouts and stormwater from surfaces such as driveways and patios should be diverted off the septic tank and drainfield. A small trench uphill from a drainfield can help direct water away.

9. How close to the drainfield can I install a sprinkler system?

Water lines should be at least 10 feet from all components of the septic system. Be sure all sprinkler lines are fitted with approved backflow prevention devices.

10. ... and can I put a retaining wall and drains back there?

If you are planning to put drains (interceptor, French, curtain) or retaining walls within 30 feet of ANY PART of the septic system. Never cut through drainfields for drains, walls or irrigation lines. French drains are notorious for carrying pollution from septic systems into water bodies or streets.

11. Okay, you've told me everything I can't do. What can I do to improve the appearance of my drainfield?

Planting your drainfield will be much different from other experiences you may have had landscaping. First, it is unwise to work the soil, which means no rototilling. Parts of the system may be only six inches under the surface. Adding two to three inches of topsoil should be fine, but more could be a problem. Second, the plants need to be relatively low-maintenance and low-water use. You will be best off if you select plants for your drainfield that once established will not require routine watering.

12. How can I make the drainfield area look natural?

A meadow with a mix of native grasses and shallow-rooting flowers can be very attractive, and good for wildlife, too. The use of wildflowers with bulbs is an easy way to landscape the drainfield and have two to three seasons of color. Daffodil and crocus bulbs are easy to naturalize and both are reasonably drought tolerant and will return year after year.

When selecting wildflower seed, there are several important considerations:

• Be sure the seed is viable and not leftover from the previous year. Many mixes currently available may not be well suited for our Northwest climate.
• As with the plant lists above, seed selection must be based on the amount of sun. Most landscape or plant suppliers have a variety of native seed mixes for all types of sun-shade situations.
• The seed mix needs to be a blend of annual and perennial seeds. Avoid wildflower seeds that contain knapweed, hawkweed, or other noxious weeds. Packets of wildflowers from out of state may contain weeds considered a nuisance here in Ohio. Look for Ohio state labeled packages that say "no noxious weeds" or "no detectable weeds."
• If your drainfield currently has grass, you cannot just spread the seed over the grass and expect it to grow. Remove the grass in small areas, six inches or so in diameter, and sow the seed in those areas. The grass needs to be kept out of the area until the seed has germinated and is large enough to compete with the grass.

• May is generally the best month to sow wildflower seeds, when we still get enough rain to keep the seeds moist during germination. If we have a dry month, sprinkle the seeds with water twice a week. 

Plants You Can Grow On Standard Leachfields

Following are three lists of shallow-rooted plants you can grow on standard drainfields or mounds, including groundcovers, ferns, and ornamental grasses.

DEEP SHADE (receives no direct sun)

• Carpet Bugle (Adjudge reptans): an aggressive groundcover with blue flowers in the spring.
• Japanese Spurge (Pachysandra terminalis): an aggressive evergreen groundcover; once established, it forms a thick cover, minimizing weeds.
• Periwinkle (Vinca minor): an evergreen groundcover with periwinkle blue flowers in the spring. Moderately drought tolerant in shady areas.
• Sword Fern (Polystichum munitum): a native evergreen fern that in a shady location is very tolerant of our dry summer months. Easy to grow.
• Irish Moss (Sagina): not a true moss, but a good look-alike and much easier to grow. Does best when mixed with ferns and other plants.

Note: Do not mix carpet bugle, Japanese spurge and periwinkle - select one.

PARTIAL SUN AND SHADE (receives about four hours of afternoon sun)

• Blue Star Creeper: an attractive, fast-growing groundcover with tiny blue flowers.
• Vaccinium "Well's Delight"(Vaccinium crassifolium): shiny, dark evergreen leaves with dainty pinkish flowers. A good, three-inch-tall groundcover for partial sun.
• Creeping Rubus (Rubus pentalobus): this is a species of ornamental bramble, but its leaves and small flowers are much more decorative than its thorny cousins. The rooting carpet of stems can easily grow four feet a year.
• Carpet bugle and sword fern (see above) are also suitable, but the fern will not be as drought tolerant as in the shade.

SUN (receives full sun all day or about eight hours)

• Kinnikinnick (Arctostaphylos uva-ursi): a native evergreen groundcover known for its drought tolerance once established. Requires a well-drained soil; not tolerant of wet areas.
• Blue-silver fescue (Festuca cinema): an ornamental grass with blue-silver blades. A short, clumping grass requiring a well-drained soil, not drought tolerant.
• Blue oat grass (Helictotrichon sempervirens): an ornamental grass with stiff evergreen blue blades. Requires well-drained soil.
• Fountain grass (Pennisetum alopercuroides): an attractive fountain grass with arching stems bearing soft, bottlebrush clusters of fuzzy flowers. Grows to about 1 1/2 to 2 feet and is tolerant of moist soils, unlike some other ornamental grasses.
• Vaccinium "Well's Delight" and Creeping rubus, noted above, are also suitable.

Additional Information

For more information on septic-system care, inspection and maintenance, call GullettSanitation Service Inc. at 513-734-2227 or Email  us at: CompanyWebmaster with questions or comments.