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How to Plant Over a Sand Mound Septic System

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Septic tanks are eyesores in the landscape. As tempting as it may be to start planting flowers and shrubs as a cover, you must find septic-safe species first. Fortunately, there are many plant species suitable for planting on and around septic tanks. A few species suitable for septic tank planting include lupines, pot marigolds, blue-eyed grass, mosses, Irish moss, bunny tails grass, creeping Jenny, creeping Charlie, bee balm, morning glories, dandelions, catnip, standing cypress and miniature sedums. Choose only shallow-rooted plants that will not spread out and into septic lines. Keep in mind that the plants may have to be moved or risk being destroyed if septic tank maintenance is ever required.

Planting Seeds on the Septic Tank

Use a heavy-tined rake to loosen the soil over the septic tank. Be careful to avoid digging too deeply, as this can possibly damage the tank or pipes.

Spray the area with water. This helps the seeds to stick better than on dry soil.

Mix the flower seeds with dry sand. The sand promotes better seed distribution. Use sand of a different color than the septic tank sand to aid in seeing where seeds are dropping.

Use a large-holed shaker (sugar shakers work well) or your hands to broadcast the seed mixture across the septic mound.

Cover the seeds with the recommended amount of soil for their species. Check the seed packet for directions for the specific type of seeds you are planting.

Water the seeds with a gentle spray of water. Keep the soil slightly moist until the seedlings have two or three sets of true leaves.

Potted Septic Tank Garden

Pot all invasive, deep-rooted shrubs, flowers and trees for use on and around septic tanks. Avoid planting them directly in the ground, as their roots will grow into the surrounding septic lines. Invasive plants include — but are not limited to — willow, Chinese elm and maple trees.

Mix enough compost and native soil together to create a friable potting soil.

Add enough potting soil to the pots to bring the plants' top roots 1 to 2 inches below the pots’ surface.

Pot the plant, firming the soil around its roots with your fingers.

Saturate the soil with water to settle the plant and remove any remaining air pockets.

Arrange the potted plants around the septic tank. Avoid placing anything heavy directly over the lines or the tank itself.


Use drought-tolerant plants over the septic mound. Although the tank is wet inside, it is often very dry and hot on top of the system.

Using low-maintenance species also prevents the septic tank from being exposed to unnecessary traffic and water.


Avoid using synthetic fertilizer and other chemicals around the septic tank. Worm compost is a good alternative to synthetic fertilizer.

Never grow edible plants on top of a septic system. You can't eat anything grown in the soil on or around a septic system.

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