Image gallery for: Garden how to fill a deep raised bed cheap and easy 1 start with the base bulk materials use cheap materials like logs branches dead leaves straw or cardboard to fill the bottom ⅓ to ½ of the bed 2 add organic matter layer compostable kitchen scraps unfinished compost or manure to enrich the soil over time 3 add a middle layer use garden soil compost and aged mulch or wood chips for good drainage and nutrients 4 top layer high quality soil fill the top 6–12 inches with nutrient rich compost potting soil or a mix of garden soil and compost 5 water and settle water each layer as you build to settle the materials and promote decomposition 6 mulch the surface add mulch to retain moisture and suppress weeds