Many homeowners in South Carolina want to know what tin can be grown, if annihilation, over their septic drain field. As an increasing number of people motion into rural areas throughout the land, this outcome becomes more mutual. A septic organization represents a significant investment, so some understanding of its workings volition allow a homeowner to protect and care for his investment properly. Proper intendance and maintenance of the septic organisation will salvage fourth dimension and coin while protecting the environment.

How a Septic Drain Field Functions

Understanding how a septic system functions is essential to making sound decisions about how to best landscape over the drain field. A standard septic tank will separate solids from liquids. The liquid effluent, or wastewater, will so menstruum from the tank into a series of bleed lines that allow the effluent to slowly percolate down through the soil in the drain field. Many different soil microbes will human action to filter and cleanse the liquid effluent before the harmful bacteria in it has a run a risk to accomplish basis water. These soil microbes require oxygen to office optimally, and perform less finer in compacted and/or saturated soils. This is why it is recommended to continue excessive traffic off the drain field to avoid over-compaction of the soils. It is too recommended to keep excessive wet from flowing over the bleed field. This can exist accomplished by diverting runoff from a roof or driveway abroad from the drain field, and making sure that irrigation systems practise not add excessive moisture. Information technology is recommended that sprinkler heads be positioned so that no irrigation water comes within x feet of the drain field.

A typical septic drain field (see Effigy i), also known as a leach field, is a serial of perforated pipes that are ready in trenches and buried with aggregates (½- to 2½-inch gravel or ½- to 4-inch rubber chips) and soil. These drain lines are at a minimum depth of vi inches and are typically 18 to 36 inches broad. The individual drain lines will unremarkably be 8½ to 10 anxiety apart (run into Figure 2). Information technology is important to note here that each bleed field organisation will vary from the next. It is important that the homeowner accept a detailed layout of their organisation (giving the locations and dimensions of individual components) for their reference.

Zosia Lawn

Zosia Lawn.
N.C. Corporative Extension

Why Carp With Landscaping the Drain Field?

There are several reasons for planting over a drain field. Mayhap the most compelling argument for planting into the bleed field would be to mitigate whatever erosion of the soil over the drain field. Another reason would be that plants aid the organisation to function more effectively by optimizing oxygen substitution and promoting necessary soil moisture removal through transpiration. Therefore, a cover of lawn turf would be the best plant encompass to institute and maintain over the drain field. On the other paw, a homeowner's reason for wanting to landscape the drain field may likewise exist that it is the simply sunny location on their property. This is often the case with new developments carved out of woodland areas. It may also exist that the drain field is in the front yard, and the homeowner wants to plant a landscape to accentuate the front of their firm. While these are certainly valid considerations, it should be noted that planting certain types of vegetation on or near a drain field is non recommended because of the threat that their associated root systems pose to the long-term functionality of the drain field. No i wants septic effluent surfacing in their g, not to mention the cost of repairs and the associated inconveniences. However, there are certainly recommendations for which plants should or should not exist planted on or around the drain field.

Plant Selection for the Drain Field

Co-ordinate to many of the articles written on this subject, shallow-rooted herbaceous plants that are well adapted to normal rainfall amounts for the area are all-time suited for utilise in a drain field planting. Plants that have aggressive, woody, water-loving, deep roots can potentially clog or disrupt the pipes in the system, causing serious damage that tin be very expensive, very messy and threaten the environment. The key is to select plants that will satisfy landscaping needs while posing equally minimal a threat to the drain field equally possible.

Star-flower (Trientalis borwalis)

Star-flower (Trientalis borwalis).
Rob Routledge, Sault College, Bugwood.org

Herbaceous Plants

Shallow-rooted herbaceous plants refer to flowering annuals and perennials (including bulbs), turfgrass, weeds and many groundcovers. Equally previously mentioned, these plants are unlikely to clog and damage drain lines. Many of our native grasses in South Carolina as well as not-native grasses are well suited for use in a drain field planting. Just remember that larger plants typically have larger root systems, so tall grasses like Miscanthus spp. or pampas grass are definitely not recommended for use in this instance. Mixes of wildflowers, bulbs and grasses provide a suitable, bonny vegetative comprehend.

Still, fifty-fifty when planting shallow-rooted plants there are some general guidelines to consider when planting on a drain field:

  • Never add additional soil over the drain field unless it is a minimal amount used to restore an area that may have been eroded or pulled upwardly by removing another plant.
  • Try not to be overly zealous when tilling the soil for planting. Call back that the bleed lines may exist as shut as half-dozen inches from the soil surface. Double-digging is certainly not recommended!
  • Always habiliment gloves when working with the soil in the drain field expanse to minimize your exposure to the soil and any harmful organisms in information technology. This applies to many gardening activities such as earthworks, planting and weeding.
  • When planting directly over a line trench, avoid using found species that require frequent dividing.
  • If a groundcover is called, do not employ species that create a thick, dumbo awning that would shade the footing below and collect organic debris. This situation can create an environment of cool, moist soil that does not allow enough evaporation and soil oxygen commutation from the soil surface for optimal functionality of the system.
  • Choose species that are well adjusted to the soils and boilerplate rainfall in the area. This may reduce the demand for supplemental fertilizers and water, which can compromise the functionality of the organization.

    Switchgrass (Panicum virgatum).

    Switchgrass (Panicum virgatum).
    James H. Miller, USDA Forest Service, Bugwood.org

  • Minimize traffic over the drain field. Select low maintenance species and endeavour to programme for a minimum of pes traffic and activity over the area.
  • Go along the mulch layer to a minimum then as to not restrict evaporation of soil moisture.

Selected List of Plants for Use on Septic Drain Fields

Herbaceous plants, such equally annuals, perennials, bulbs and ornamental grasses are generally the best choices for employ on a septic bleed field. Ornamental grasses also offering the advantages of having a fibrous root system that holds soil in identify, and providing yr-round encompass. The following listing of suggested plants is not meant to exist spread-out, but rather a small sampling of suggested plants for use. Suggested plants should exist further investigated to ensure that private site atmospheric condition and location are conducive to that plant'southward cultural requirements, especially soil moisture and sunlight elapsing.

Ornamental Grasses:

For Sun (plants marked with an * will tolerate light shade):

  • Andropogon gerardii – Big Bluestem
  • Andropogon gyrans – Elliot Bluestem
  • Bouteloua curtipendula – Sideoats Grama
  • Carex appalachica – Appalachian Sedge
  • Carex elata – Aureate Sedge *
  • Carex pennsylvanica – Pennsylvania Sedge *
  • Chasmanthium latifolium – River Oats *
  • Danthonia spp. – Oatgrass
  • Eragrostis curvula – Weeping Love Grass
  • Festuca ovina – Blue Fescue
  • Melica mutica – Two-flowered Melic Grass
  • Muhlenbergia capillaries – Pink Muhly Grass
  • Oplisemenus setarius – Crinkly Leaf *
  • Panicum virgatum – Switchgrass
  • Piptochaetium avenaceum – Green Needle Grass
  • Schizachyrium scoparium – Lilliputian Bluestem
  • Sorghastrum nutans – Indiangrass
  • Spartina bakerii – Baker'southward Cordgrass
  • Sporobolus heterolepis – Prairie Dropseed *
  • Stipa gigantean – Behemothic Needle Grass
  • Stipa tenuissima – Texas Needle Grass
  • Tridens flavus – Purpletop *

Bulbs:

  • Agapanthus spp. – Lily-of-the-Nile
  • Allium spp. – Ornamental Onions
  • Anemone spp. – Anemone/Windflowers
  • Colchicum spp. – Fall Crocus
  • Crocosmia spp. – Montbretia
  • Crocus spp. – Crocus
  • Dahlia spp. – Dahlias
  • Endymion hispanica – Spanish Bluebell
  • Galtonia candicans – Summer Hyacinths
  • Gladiolus spp. – Gladioli
  • Hyacinthus orientalis – Mutual Hyacinth
  • Ipheion uniflorum – Star Blossom
  • Iris spp. – Iris
  • Leucojum aestivum – Summer Snowflake
  • Lilium spp. – Lilies
  • Muscari spp. – Grape Hyacinths
  • Narcissus spp. and hybrids – Daffodils
  • Tulipa spp. and hybrids – Tulips

Perennials:

For Shade (plants marked with a * volition tolerate the most shade):

  • Acanthus mollis – Bear'southward Breech
  • Alchemilla mollis – Lady'southward Drape
  • Amsonia tabernaemontana – Bluish Star
  • Aquilegia spp. – Columbine
  • Arum italicum – Painted Arum *
  • Asarum spp. – Wild Gingers *
  • Aspidistra elatior – Bandage Iron Plant *
  • Astilbe x arendsii – Astilbe
  • Begonia grandis – Hardy Begonia
  • Bergenia cordifolia – Heartleaf Bergenia
  • Brunnera macrophylla – Siberian Bugloss
  • Ceratostigma plumbaginoides – Plumbago
  • Chelone oblique – Turtlehead
  • Chrysogonum virginianum – Green and Gilt
  • Cimicifuga spp. – Bugbane/Cohosh
  • Convallaria majalis – Lily-of-the-Valley *
  • Cyclamen spp. – Hardy Cyclamen
  • Dicentra spp. – Bleeding Middle
  • Digitalis spp. – Foxglove
  • Epimedium spp. – Barrenwort *
  • Ferns * (near)
  • Galium odoratum – Sweet Woodruff *
  • Geranium maculatum – Cranesbill Geranium
  • Gillenia trifoliate – Bowman's Root
  • Helleborus foetidus – Bearfoot Hellebore
  • Helleborus orientalis – Lenten Rose
  • Heuchera spp. – Coral Bells
  • Hosta spp. – Plantain Lily
  • Lamium maculatum – Spotted Dead Nettle *
  • Lobelia cardinalis – Cardinal Bloom *
  • Lobelia siphilitica – Great Blue Lobelia *
  • Mertensia virginica – Virginia Bluebells *
  • Myosotis sylvatica – Forget-me-not
  • Phlox divaricata – Wild Sweet William
  • Phlox stolonifera – Creeping Woodland Phlox
  • Polygonatum spp. – Solomon's Seal *
  • Primula spp. – Primrose
  • Pulmonaria spp. – Lungwort *
  • Salvia koyame – Japanese Yellow Sage
  • Saxifraga stolonifera – Strawberry Begonia
  • Shortia galacifolia – Oconee Bells *
  • Smilacina racemosa – False Solomon's Seal
  • Spigelia marilandica – Indian Pink
  • Thalictrum spp. – Meadow Rue
  • Tiarella spp. – Foam Bloom *
  • Tradescantia virginianae – Spiderwort *
  • Tricyrtis spp. – Toad Lily *
  • Trillium spp. – Wake Robin *
  • Viola spp. – Violet *

For Sunny, Dry out Conditions:

  • Achillea spp. – Yarrow
  • Agave parryi – Hardy Century Establish
  • Andropogon spp. – Bluestem Grass
  • Anthemis tinctoria – Golden Marguerite
  • Artemisia spp. – Wormwood
  • Asclepias tuberosa – Butterfly Weed
  • Aster novae-angliae – New England Aster
  • Baptisia spp. – False Indigo
  • Belamcanda chinensis – Blackberry Lily
  • Coreopsis spp. – Coreopsis
  • Delosperma cooperi – Hardy Ice Plant
  • Eupatorium purpureum – Joe-Pye Weed
  • Euphorbia spp. – Spurge
  • Gaillardia spp. – Blanket Flower
  • Gaura lindheimeri – Gaura
  • Helianthus spp. – Perennial Sunflower
  • Hemerocallis spp. and hybrids – Daylily
  • Hesperaloe parviflora – Imitation Cherry-red Yucca
  • Kniphofia uvaria – Red Hot Poker
  • Lantana spp. – Lantana
  • Lavandula x intermedia – Provence Lavander
  • Liatris spp. – Gayfeather
  • Limonium latifolium – Sea Lavander
  • Nepeta spp. – Catmint
  • Oenothera spp. – Evening Primrose, Sundrops
  • Opuntia humifusa – Prickly Pear Cactus
  • Perovskia atriplicifolia – Russian Sage
  • Phlomis spp. – Jerusalem Sage
  • Plumbago auriculata – Plumbago
  • Rudbeckia spp. – Black-eyed Susan
  • Ruellia brittoniana – Mexican Petunia
  • Salvia greggi – Texas Sage
  • Santolina spp. – Lavander Cotton
  • Sedum spp. – Stonecrop
  • Sempervivum tectorum – Hens & Chickens
  • Setcrasea pallida – Purple Heart
  • Solidago odora – Sugariness Goldenrod
  • Stachys byzantine – Lamb's Ear
  • Verbena spp. – Verbena

Hardy Begonia (Begonia spp.).

Hardy Begonia (Begonia spp.).
Howard F. Schwartz, Colorado State Academy, Bugwood.org

Woody Plants

Woody plants are more often than not larger shrubs and trees that have woody stems and other woody found parts that do not dice back to the ground in winter. These plants are much more likely to crusade serious damage to drain fields with their root systems. Trees with very aggressive root systems that should exist avoided include willows, crimson and silver maples, beeches, birches, elms and poplars. Some trees with less aggressive root systems include cherries, crabapples, dogwoods, hemlock and oaks. To reduce the associated financial risk and emotional stress of a failed system, institute trees at least as far abroad as their estimated root spread at maturity. There are two methods used to approximate tree root spread. Ane dominion of thumb is that roots extend out from the tree 2 to 4 times the diameter of the awning. Some other is that tree roots spread out one to three times the height of the tree. These estimates should be considered a bare minimum, and to reduce the chance, the copse should be planted even further abroad from the drain field.

Shrubs with less ambitious root systems should never be planted any closer than 10 feet and small less aggressive trees no closer than twenty feet from the drain field. Planting these less-aggressive species, such every bit boxwoods, hollies or arborvitae towards the drier ends of the drain lines may also reduce the risk for problems down the route.

An important point to think is that the drain field needs sun to perform optimally, and so do non shade the surface area heavily with copse and shrubs. If the homeowner decides that it is worth the risk to plant less aggressive, gristly-rooted shrubs or small-scale trees in the drain field, at least found them between the drain lines. In South Carolina these trenches are typically 8½ to x anxiety apart. However, not all systems are created equal. Refer to your layout chart or diagram that should provide the locations and dimensions of your organization's components. Delight be aware that planting trees and shrubs near the bleed field is inherently risky, merely if you are willing to take the adventure of potentially dissentious the drain lines in order to enjoy the landscape, then keep these guidelines in listen when planning.

Strategies to Reduce the Threat of Root Organization Damage

Proper soil training tin can discourage roots from damaging bleed lines. The idea is to provide an area for root growth away from the drain lines to forbid roots from seeking out water and nutrients in the drain field. It is recommended to dig as wide a planting hole as possible for the tree or shrub (at least 2 – iii times the width of the canopy), excavation out farther on the side of the pigsty contrary the bleed field. The reasoning backside this is to offering the roots a "path of to the lowest degree resistance" in the soil away from the drain field.

In that location are too several root barriers to consider using. These tin can range from rudimentary materials to more expensive geotextiles that are impregnated with herbicides to restrict root growth. In order for the barrier to exist effective, it needs to exist buried upwards to a depth of at least 2 anxiety. Ideally the barrier should run the length of the drain field to prevent tree roots from flanking the bulwark and disturbing the drain lines. Continue the root barrier at to the lowest degree 5 feet or more from the drain line, and then at to the lowest degree another 5 feet from the planting hole. Simply remember to never create a circle effectually the root ball of the tree with the barrier, which would create bug for the tree as it grows.

Will the Effluent Affect my Growing Atmospheric condition?

The effluent in the septic drain field does affect growing conditions. Whatever goes downwards the drain in a particular household influences the composition of the effluent. The vast bulk of household chemicals are alkaline (pH to a higher place 7) and thus raise the pH of the effluent. However, a properly functioning septic system has anaerobic digestion by leaner in the tank that tends to keep the effluent pH closer to neutral. Bearing this in listen, it is appropriate to test the soil pH and to plant species that are largely pH adaptable. Some other cistron to consider is that salinity levels have the potential to be high, so selecting species with a known tolerance for salt is advisable if a soil test reveals high levels of sodium.

Growing Vegetables Over a Septic Drain Field

Although the drain field may seem to be the ideal place to accept a vegetable garden, it is not recommended. Even though different soil types differ in their power to filter contaminants out of the effluent, there is no way to be admittedly sure that everything is being filtered out. Therefore information technology is not recommended to found vegetables in a septic drain field because of the health risks associated with bacterial contamination. Likewise, vegetable gardening requires frequent cultivation of the soil, supplemental watering and fertilization. None of these practices are recommended for a drain field. Using a raised bed is also not recommended. The additional soil over the drain field reduces the effectiveness of the system to filter the effluent considering information technology interferes with evaporation of soil moisture.

Conclusion

A layer of vegetation over the bleed field, such equally a lawn, is recommended to hold soil in place and increase the efficiency of the arrangement. Yet, certain guidelines should be followed to avoid costly and unpleasant experiences. Perhaps the best advice would exist to keep the landscaping over this area gratuitous of trees and shrubs. The optimal performance of your septic organisation should be the foremost consideration, but a cost/do good assay of using certain plants volition take to be considered by each homeowner on an individual basis.

This fact sheet was largely adjusted, with permission, from Virginia Cooperative Extension Publication 426-617: "Planting on Your Septic Bleed Field" available at: http://pubs.ext.vt.edu/426/426-617/426-617.html.

Figures 1 and 2 used with permission from SC DHEC: http://www.scdhec.gov/health/envhlth/onsite_wastewater/docs/septic_tank_system.pdf

Figure one. Structure details for an assimilation trench

Construction details for an absorption trench

Figure 2. Construction details for an private sewage disposal system

Construction details for an individual sewage disposal system