Calculate the amount of soil you will need (cubic feet/yards) using the dimensions of your raised garden bed. Keep in mind that the number should include the soil mixed in with compost. Your soil mixture should be 60% topsoil, 30% compost, and 10% potting soil. As soil can be quite expensive, we suggest you try the Hugelkultur method if you want to save money. Once you have obtained the soil, fill it near the top. The exact amount is determined by the type of plants you will be growing and personal preference. Make sure to refrain from tilling the soil as this can dry it out.