Many people make the mistake of planting trees and shrubs on or near their septic systems. Improperly locating landscape plants around the septic system can result in one or all of the following:
- Roots growing into the septic tank
- Roots growing into the piping
- Roots growing into the leach field
- Roots plugging lines
- The drainage field not being able to breathe
Trees and shrubs should never be planted on or near septic systems because of the ability of the roots to travel. This traveling can and will cause problems. Avoid these problems by choosing the correct plants. Remember, the leach field is the most expensive part of the system, and you will want to protect it from damage.
So what is safe to plant over a septic system or disposal field?
Generally speaking, any shallow-rooting herbaceous plants are OK to plant over or near septic tanks, distribution boxes, or disposal fields. Native grasses, wildflowers, yarrow, chamomile, and clover are plants that can also be used safely. Others include:
- Ornamental grasses
- Carpet heathers
- Ground Ivy
- Sweet Woodruff
- Wild Ginger
A few things to keep in mind when planting over septic systems
- You should not be digging deep holes to plant your plants. Most disposal field piping is between 6″-12″ below the surface. Digging too deep may disrupt the effectiveness of the system which will lead to premature failure.
- You should always wear gloves when planting in the soil around your septic system. The water from the system, called effluent, can contain bacteria and fungus which can make you very ill. Be extremely careful about getting the soil anywhere near your mouth.
How about vegetables?
As a general rule, no. Some folks may say it is fine to grow vegetables over your septic system, but after reading about how the effluent contains bacteria and viruses, do you really want to? Vegetables that actually root IN the soil are definitely not something you would want to eat anyway. These include carrots, beets, potatoes, etc. Other vegetables that grow on the surface may be contaminated by pathogens that splash up from the soil surface during watering or during rain.
If you absolutely HAVE to plant a tree or shrub near your septic system (within 20 feet), here are a few good and not so good choices:
Not so good:
- Beeches Fagus spp.
- Birches Betula spp.
- Elms Ulmus spp.
- Poplars Populus spp.
- Red Maple Acer rubrum
- Silver Maple Acer saccharinum
- Willows Salix spp.
- Blue Mist Spirea
- Cherries Prunus spp.
- Crabapples Malus spp.
- Dogwoods Cornus spp
- Hemlock Tsuga spp.
- Oaks (red, scarlet, white) Quercus (rubra, coccinea, alba)
- Pines Pinus spp.
- Sourwood Oxydendrum arboreum
You’ll notice I said better and not best. Although I just supplied a list of better plants, it does not mean that you will never have problems if you plant them near your system, it means they are less likely to cause harm than the previous list.