Get matched with top mulch and topsoil pros in East Glacier Park, MT

While you can put gravel directly on dirt, it won’t be very stable. It also won’t block out any weeds. Most experts recommend layering weed barrier and a layer of packed sand or other foundation material to prevent the gravel from sinking into the earth and being overtaken by weeds.

To prepare your yard for river rocks, smaller rocks may require laying landscape fabric to keep the stones from sinking into the ground while encouraging proper water drainage. You should also clear the land of weeds and larger boulders and, in some cases, test the density of the soil to ensure it can handle the weight.

Sand is a common sublayer for hardscape features like driveways, paver patios, and more. Most projects that involve sand require a 1-inch layer to promote evenness, drainage, and weight distribution. For further drainage, most projects have a 6-inch minimum layer of gravel beneath the sand. 

Yes, it is possible to add too little mulch. Anything less than 1 inch will likely result in too little coverage around your plants, allowing weeds to grow through and minimizing the positive effects that a deeper bed of mulch would have, like maintaining proper soil moisture and insulating the ground.