i made a partially raised garden to use for my hops, though i am looking to add to the existing soil and mix in a bunch of my own compost and some better quality soil that what is there now.. what would be the best product to mix with my natural soil (which doesn't' seem to great) along with the compost.. would like a miracle gro potting soil mix be good, or would just some topsoil with some peat added in be ok? i really don't want to spend too much money but i need to add some material to what i have there now