Soil mix for container bamboo
I'm looking to plant some boo in two large containers in my city backyard. Each container will be about 3' wide, 8' long, and 2' wide and holds approximately 300 gallons.
My question is what is the best soil mix to use to fill this beast? I can't find ingredients like peat moss and perlite in large enough quantities, cheaply enough to use.
I am planning on buying some screened top soil and compost in bulk (by the truckload) but am stuck as to what else I could mix in to reduce compaction and ensure aeration of the roots that the bamboo would be ok with. Should I be looking at masonry sand, or pea gravel, or something else entirely?