Best Garden Soil Mix Diy . Soil mix vines to tines. In this recipe, coarse sand, sphagnum peat moss, and. DIY Potting Soil 6 Homemade Potting Mix Recipes for the Garden from www.pinterest.com First, figure out how many cubic feet of total soil mix you would need: 6 gallons sphagnum peat moss or coir fiber. If you have a large enough container, just mix equal parts peat moss, compost, and vermiculite and then add it to the raised bed.