Get the biggest bale of promix that you can find(they come in big bales)about the same size as the largest peet bales and cost about $25. mix in a box of blood meal and a box of bone meal( about a litre each) and a couple of bags of sheap manure, add a couple of cups of wood ash and a few shovelfuls of compost.Then add some myccorrizae inoculant. all of these should be available at a good garden market except the wood ash

happy growing