Safe Plants to Grow Over Septic Tanks and Drain Fields. Plants over a septic field can help to prevent erosion and suck up excess moisture from the drain field. 1 The best types of plants are grasses, groundcovers, and some shallow-rooted shrubs and trees.
According to the University of Maryland Extension, when it comes to a septic system, ``it is best to only have grass planted above and around the system. Shallow rooted plants, small shrubs, and flowers usually can be safely planted near and above the system.''
Consider shallow-rooted trees and shrubbery (such as cherry trees, dogwood trees, holly shrubs, azalea shrubs and boxwood shrubs) for areas around the septic system, but keep them at least 10-15 feet away from your tank.
This is fine, so long as they are at least 50 feet away from your septic system and drain field. Trees that can be safely planted closer to the drain field include ornamental trees like dogwood, cherry and crabapple, hemlock of the red, scarlet and white oak varieties, and small pines such as Mugo pines.
Soft, non-woody plants help contain the moisture around the septic field, while the tender plants allow easy access to components of your septic system. Your best bet is to go with herbaceous plants. These are shallow-rooted, flowering annuals and perennials such as: Tall fescue.
Do: Plant grass or keep existing native vegetation. These are the best covers for your drainfield. Direct all surface drainage away from the septic system.
Boxwood (Buxus)
Boxwoods have shallow root systems, so they can easily be planted near your foundation without worry.
Choose plants with shallow roots, such as ornamental grasses, groundcovers, annuals, or perennials like azaleas, hydrangeas, lavender, or hollyhocks.
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 fems. The key to planting over the drainfield is to select shallow-rooted, low-maintenance, low-water-use plants.
Many studies have shown that the roots of these wildflowers do not interfere with septic systems pipes. In fact, wildflowers and native grasses actually absorb the nutrients discharged into septic beds better than turf! This is ecological landscaping at its best!
In addition to the potential contamination from pathogens, crops grown above your drainfield may also be exposed to household chemicals that are still present in effluent before it filters through the drainfield. Many of these are not safe for your septic system, let alone safe for human consumption.
ANSWER: Our experts and most pumpers agree that no deep rooting planting should be within 20 feet of your septic system or leach field – it's best to keep all these plants 20-50 feet away, 20 feet being the absolute closest to your system.
Household septic tanks are typically pumped every three to five years. Alternative systems with electrical float switches, pumps, or mechanical components should be inspected more often, generally once a year.
Next to planting deep-rooted plants, mulch is the least septic-friendly landscaping practice. As a general rule, you should avoid mulching directly over the drainfield.
Silver maple tree
They might be prized for their vibrant colour in autumn, but their root systems are one of the most invasive of all. As the roots enlarge, silver maple trees have been known to crack driveways, pavements, foundations and pipes. It's best to avoid planting this tree altogether.
1. Hinoki Cypress (Chamaecyparis) This dwarf, needled evergreen is originally from Japan and is safe to plant near a foundation. It also won't outgrow its space the way that arborvitae or larger evergreens tend to do.
Known as the world's most massive tree, giant sequoias never stop growing and can reach heights of 300 feet and weigh over 600 tons. They are also among the oldest living organisms on earth and can live to be 3,000 years old.
Typically, the drainfield consists of three to five trenches that are 18 to 24 inches deep, up to 100 ft long, with a perforated pipe in 12 to 18 inches deep gravel covered by 12 inches of soil.
Essential oils are considered safe for septic systems when used in small amounts. Diluted essential oils, like wild orange oil, pine oil, citrus oil, tea tree oil, or lavender oil, used for occasional cleaning or diffusing, are unlikely to harm your septic system.
Creeping Stonecrops (Sedum spp.)
The plants have shallow roots, so they can be grown on very thin soil. Full sun brings out the brightest foliage colors, which can be aqua, teal blue, yellow, lime green, burnt orange, red or maroon (as well as green). Sedums are evergreen, so they also provide winter interest.