Anybody out there ever mixed up their own raised bed soil mix? If so, what products and ratio did you use? I am looking at possibly blowing in a soil mix for a raised garden at a facility above a parking garage. There is a company that offers a raised bed mix here, but I think I could probably make it cheaper myself (I have most of the ingredient on hand). I believe I could use a mixture of high quality (mature) compost, pine bark fines, and sand. This mixture will be 32" deep and will be compacted in - I want to make sure I have enough sand in the mix to make the mixture drain well. Any suggestions or advice would be appreciated.