Yes, it is possible to grow flowers on the bare sand and gravel commonly used for backfilling septic fields! Native prairie plants are recommended for planting over mounds and drainfields. Nutrients in the wastewater are taken up by the plants, instead of entering the groundwater. Now that’s ecological landscaping! (Studies have shown that the roots of prairie plants do not clog septic system pipes.) For septic systems that have received topsoil over the sand and gravel backfill you may use the Short Prairie for Medium Soils Mix.